diff --git a/changelog/unreleased/SOLR-18367-waitforfinalstate-default-true.yml b/changelog/unreleased/SOLR-18367-waitforfinalstate-default-true.yml
new file mode 100644
index 00000000000..cb8f1d459e7
--- /dev/null
+++ b/changelog/unreleased/SOLR-18367-waitforfinalstate-default-true.yml
@@ -0,0 +1,16 @@
+# See https://github.com/apache/solr/blob/main/dev-docs/changelog.adoc
+title: >
+  `waitForFinalState` now defaults to `true` for CREATE, ADDREPLICA, CREATESHARD, SPLITSHARD, and
+  MOVEREPLICA, so these Collections API commands wait for affected replicas to become active before
+  returning. BALANCE_REPLICAS, MIGRATE_REPLICAS, and REPLACENODE keep the previous `false` default,
+  since they can each affect an arbitrary number of replicas cluster-wide. Set the system property
+  `solr.cloud.waitForFinalState.enabled` on a Solr node to override the default (either direction)
+  cluster-wide, for all 8 commands.
+type: changed
+authors:
+  - name: Serhiy Bzhezytskyy
+links:
+  - name: SOLR-18367
+    url: https://issues.apache.org/jira/browse/SOLR-18367
+  - name: SOLR-17712
+    url: https://issues.apache.org/jira/browse/SOLR-17712
diff --git a/solr/api/src/java/org/apache/solr/client/api/model/BalanceReplicasRequestBody.java b/solr/api/src/java/org/apache/solr/client/api/model/BalanceReplicasRequestBody.java
index 4ebb3a317e2..d7458d16df0 100644
--- a/solr/api/src/java/org/apache/solr/client/api/model/BalanceReplicasRequestBody.java
+++ b/solr/api/src/java/org/apache/solr/client/api/model/BalanceReplicasRequestBody.java
@@ -24,9 +24,8 @@ public class BalanceReplicasRequestBody {
 
   public BalanceReplicasRequestBody() {}
 
-  public BalanceReplicasRequestBody(Set<String> nodes, Boolean waitForFinalState, String async) {
+  public BalanceReplicasRequestBody(Set<String> nodes, String async) {
     this.nodes = nodes;
-    this.waitForFinalState = waitForFinalState;
     this.async = async;
   }
 
@@ -36,20 +35,6 @@ public BalanceReplicasRequestBody(Set<String> nodes, Boolean waitForFinalState,
   @JsonProperty(value = "nodes")
   public Set<String> nodes;
 
-  /**
-   * @deprecated Solr is moving toward always waiting for final state, with no option to opt out;
-   *     once that happens, this parameter will have no effect and will likely be removed. See
-   *     SOLR-17712.
-   */
-  @Schema(
-      description =
-          "If true, the request will complete only when all affected replicas become active. "
-              + "If false, the API will return the status of the single action, which may be "
-              + "before the new replica is online and active.")
-  @JsonProperty("waitForFinalState")
-  @Deprecated(since = "9.10")
-  public Boolean waitForFinalState = false;
-
   @Schema(description = "Request ID to track this action which will be processed asynchronously.")
   @JsonProperty("async")
   public String async;
diff --git a/solr/api/src/java/org/apache/solr/client/api/model/MigrateReplicasRequestBody.java b/solr/api/src/java/org/apache/solr/client/api/model/MigrateReplicasRequestBody.java
index 9622559cb54..a4e00a59561 100644
--- a/solr/api/src/java/org/apache/solr/client/api/model/MigrateReplicasRequestBody.java
+++ b/solr/api/src/java/org/apache/solr/client/api/model/MigrateReplicasRequestBody.java
@@ -25,10 +25,9 @@ public class MigrateReplicasRequestBody {
   public MigrateReplicasRequestBody() {}
 
   public MigrateReplicasRequestBody(
-      Set<String> sourceNodes, Set<String> targetNodes, Boolean waitForFinalState, String async) {
+      Set<String> sourceNodes, Set<String> targetNodes, String async) {
     this.sourceNodes = sourceNodes;
     this.targetNodes = targetNodes;
-    this.waitForFinalState = waitForFinalState;
     this.async = async;
   }
 
@@ -42,20 +41,6 @@ public MigrateReplicasRequestBody(
   @JsonProperty
   public Set<String> targetNodes;
 
-  /**
-   * @deprecated Solr is moving toward always waiting for final state, with no option to opt out;
-   *     once that happens, this parameter will have no effect and will likely be removed. See
-   *     SOLR-17712.
-   */
-  @Schema(
-      description =
-          "If true, the request will complete only when all affected replicas become active. "
-              + "If false, the API will return the status of the single action, which may be "
-              + "before the new replicas are online and active.")
-  @JsonProperty
-  @Deprecated(since = "9.10")
-  public Boolean waitForFinalState = false;
-
   @Schema(description = "Request ID to track this action which will be processed asynchronously.")
   @JsonProperty
   public String async;
diff --git a/solr/api/src/java/org/apache/solr/client/api/model/ReplaceNodeRequestBody.java b/solr/api/src/java/org/apache/solr/client/api/model/ReplaceNodeRequestBody.java
index f3f49a876f8..0ee145c918d 100644
--- a/solr/api/src/java/org/apache/solr/client/api/model/ReplaceNodeRequestBody.java
+++ b/solr/api/src/java/org/apache/solr/client/api/model/ReplaceNodeRequestBody.java
@@ -23,9 +23,8 @@ public class ReplaceNodeRequestBody {
 
   public ReplaceNodeRequestBody() {}
 
-  public ReplaceNodeRequestBody(String targetNodeName, Boolean waitForFinalState, String async) {
+  public ReplaceNodeRequestBody(String targetNodeName, String async) {
     this.targetNodeName = targetNodeName;
-    this.waitForFinalState = waitForFinalState;
     this.async = async;
   }
 
@@ -36,20 +35,6 @@ public ReplaceNodeRequestBody(String targetNodeName, Boolean waitForFinalState,
   @JsonProperty("targetNodeName")
   public String targetNodeName;
 
-  /**
-   * @deprecated Solr is moving toward always waiting for final state, with no option to opt out;
-   *     once that happens, this parameter will have no effect and will likely be removed. See
-   *     SOLR-17712.
-   */
-  @Schema(
-      description =
-          "If true, the request will complete only when all affected replicas become active. "
-              + "If false, the API will return the status of the single action, which may be "
-              + "before the new replica is online and active.")
-  @JsonProperty("waitForFinalState")
-  @Deprecated(since = "9.10")
-  public Boolean waitForFinalState = false;
-
   @Schema(description = "Request ID to track this action which will be processed asynchronously.")
   @JsonProperty("async")
   public String async;
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/AddReplicaCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/AddReplicaCmd.java
index 162dc555a8a..40db1a35ee5 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/AddReplicaCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/AddReplicaCmd.java
@@ -27,6 +27,7 @@
 import static org.apache.solr.common.params.CollectionParams.CollectionAction.ADDREPLICA;
 import static org.apache.solr.common.params.CommonAdminParams.TIMEOUT;
 import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE;
+import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP;
 
 import java.io.IOException;
 import java.lang.invoke.MethodHandles;
@@ -113,7 +114,9 @@ List<ZkNodeProps> addReplica(
           "Collection: " + collectionName + " shard: " + shard + " does not exist");
     }
 
-    boolean waitForFinalState = message.getBool(WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message, WAIT_FOR_FINAL_STATE, WAIT_FOR_FINAL_STATE_DEFAULT_PROP, false);
     boolean skipCreateReplicaInClusterState =
         message.getBool(SKIP_CREATE_REPLICA_IN_CLUSTER_STATE, false);
 
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/BalanceReplicasCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/BalanceReplicasCmd.java
index 743d9f5847f..6075de80318 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/BalanceReplicasCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/BalanceReplicasCmd.java
@@ -55,7 +55,12 @@ public void call(AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList
           "'nodes' was not passed as a correct type (Set/List/String): "
               + nodesRaw.getClass().getName());
     }
-    boolean waitForFinalState = message.getBool(CommonAdminParams.WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP,
+            false);
     int timeout = message.getInt("timeout", 10 * 60); // 10 minutes
     boolean parallel = message.getBool("parallel", false);
 
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/CollectionHandlingUtils.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/CollectionHandlingUtils.java
index 02320e1e854..d7dbde98f7b 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/CollectionHandlingUtils.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/CollectionHandlingUtils.java
@@ -61,6 +61,7 @@
 import org.apache.solr.common.params.CollectionAdminParams;
 import org.apache.solr.common.params.CoreAdminParams;
 import org.apache.solr.common.params.ModifiableSolrParams;
+import org.apache.solr.common.util.EnvUtils;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.SimpleOrderedMap;
 import org.apache.solr.common.util.StrUtils;
@@ -140,6 +141,17 @@ public static EnumSet<Replica.Type> leaderEligibleReplicaTypes() {
         .collect(Collectors.toCollection(() -> EnumSet.noneOf(Replica.Type.class)));
   }
 
+  /**
+   * Reads a boolean request param, falling back to a node-level system property when the request
+   * doesn't specify one, and finally to {@code defaultValue} when neither is set. Lets an operator
+   * override a per-request default cluster-wide (e.g. via {@code -D<envProp>=false} at node
+   * startup) without a client change -- same shape as {@code CreateCollectionCmd.PRS_DEFAULT_PROP}.
+   */
+  static boolean getBoolWithEnvFallback(
+      ZkNodeProps message, String messageParam, String envProp, boolean defaultValue) {
+    return message.getBool(messageParam, EnvUtils.getPropertyAsBool(envProp, defaultValue));
+  }
+
   static boolean waitForCoreNodeGone(
       String collectionName,
       String shard,
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateCollectionCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateCollectionCmd.java
index 14291d7b941..70705233548 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateCollectionCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateCollectionCmd.java
@@ -24,6 +24,7 @@
 import static org.apache.solr.common.params.CollectionParams.CollectionAction.DELETE;
 import static org.apache.solr.common.params.CommonAdminParams.ASYNC;
 import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE;
+import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP;
 import static org.apache.solr.common.params.CommonParams.NAME;
 import static org.apache.solr.common.util.StrUtils.formatString;
 import static org.apache.solr.handler.admin.ConfigSetsHandler.DEFAULT_CONFIGSET_NAME;
@@ -111,7 +112,9 @@ public void call(AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList
     ClusterState clusterState = adminCmdContext.getClusterState();
     final Aliases aliases = ccc.getZkStateReader().getAliases();
     final String collectionName = message.getStr(NAME);
-    final boolean waitForFinalState = message.getBool(WAIT_FOR_FINAL_STATE, false);
+    final boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message, WAIT_FOR_FINAL_STATE, WAIT_FOR_FINAL_STATE_DEFAULT_PROP, true);
     final String alias = message.getStr(ALIAS, collectionName);
     log.info("Create collection {}", collectionName);
     boolean prsDefault = EnvUtils.getPropertyAsBool(PRS_DEFAULT_PROP, false);
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateShardCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateShardCmd.java
index 7c0e1633603..ae95885a2fd 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateShardCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/CreateShardCmd.java
@@ -50,7 +50,12 @@ public void call(AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList
       throws Exception {
     String extCollectionName = message.getStr(COLLECTION_PROP);
     String sliceName = message.getStr(SHARD_ID_PROP);
-    boolean waitForFinalState = message.getBool(CommonAdminParams.WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP,
+            true);
 
     log.info("Create shard invoked: {}", message);
     if (extCollectionName == null || sliceName == null)
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateCmd.java
index 2869f9866b6..1f0771e01cf 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateCmd.java
@@ -46,6 +46,7 @@
 import org.apache.solr.common.cloud.ZkNodeProps;
 import org.apache.solr.common.cloud.ZkStateReader;
 import org.apache.solr.common.params.CollectionAdminParams;
+import org.apache.solr.common.params.CommonAdminParams;
 import org.apache.solr.common.params.CoreAdminParams;
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.util.NamedList;
@@ -308,7 +309,11 @@ private void migrateKey(
             CollectionAdminParams.COLL_CONF,
             configName,
             CollectionHandlingUtils.CREATE_NODE_SET,
-            sourceLeader.getNodeName());
+            sourceLeader.getNodeName(),
+            // the getLeaderRetry(...) call below is this method's own wait; don't let
+            // CreateCollectionCmd's own wait run (and block on) first.
+            CommonAdminParams.WAIT_FOR_FINAL_STATE,
+            "false");
     String internalAsyncId = null;
     if (adminCmdContext.getAsyncId() != null) {
       internalAsyncId = adminCmdContext.getAsyncId() + Math.abs(System.nanoTime());
@@ -400,6 +405,9 @@ private void migrateKey(
     props.put(SHARD_ID_PROP, tempSourceSlice.getName());
     props.put("node", targetLeader.getNodeName());
     props.put(CoreAdminParams.NAME, tempCollectionReplica2);
+    // the syncRequestTracker below is this method's own wait; don't let AddReplicaCmd's own
+    // wait run (and block on) first.
+    props.put(CommonAdminParams.WAIT_FOR_FINAL_STATE, "false");
     // copy over property params:
     for (String key : message.keySet()) {
       if (key.startsWith(CollectionAdminParams.PROPERTY_PREFIX)) {
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateReplicasCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateReplicasCmd.java
index 779ab999197..281fe54847b 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateReplicasCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/MigrateReplicasCmd.java
@@ -50,7 +50,12 @@ public void call(AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList
     ZkStateReader zkStateReader = ccc.getZkStateReader();
     Set<String> sourceNodes = getNodesFromParam(message, CollectionParams.SOURCE_NODES);
     Set<String> targetNodes = getNodesFromParam(message, CollectionParams.TARGET_NODES);
-    boolean waitForFinalState = message.getBool(CommonAdminParams.WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP,
+            false);
     if (sourceNodes.isEmpty()) {
       throw new SolrException(
           SolrException.ErrorCode.BAD_REQUEST, "sourceNodes is a required param");
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/MoveReplicaCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/MoveReplicaCmd.java
index 635bae1e682..a9bbf0f61fd 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/MoveReplicaCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/MoveReplicaCmd.java
@@ -25,6 +25,7 @@
 import static org.apache.solr.common.params.CommonAdminParams.IN_PLACE_MOVE;
 import static org.apache.solr.common.params.CommonAdminParams.TIMEOUT;
 import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE;
+import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP;
 
 import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
@@ -72,7 +73,9 @@ private void moveReplica(
     CollectionHandlingUtils.checkRequired(message, COLLECTION_PROP, CollectionParams.TARGET_NODE);
     String extCollection = message.getStr(COLLECTION_PROP);
     String targetNode = message.getStr(CollectionParams.TARGET_NODE);
-    boolean waitForFinalState = message.getBool(WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message, WAIT_FOR_FINAL_STATE, WAIT_FOR_FINAL_STATE_DEFAULT_PROP, false);
     boolean inPlaceMove = message.getBool(IN_PLACE_MOVE, true);
     int timeout = message.getInt(TIMEOUT, 10 * 60); // 10 minutes
 
@@ -368,7 +371,11 @@ private void moveNormalReplica(
             CoreAdminParams.NAME,
             newCoreName,
             ZkStateReader.REPLICA_TYPE,
-            replica.getType().name());
+            replica.getType().name(),
+            // this method has its own watcher/latch below, conditioned on waitForFinalState;
+            // don't let AddReplicaCmd's own wait run (and block on) first.
+            WAIT_FOR_FINAL_STATE,
+            "false");
 
     NamedList<Object> addResult = new NamedList<>();
     SolrCloseableLatch countDownLatch = new SolrCloseableLatch(1, ccc.getCloseableToLatchOn());
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplaceNodeCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplaceNodeCmd.java
index 26a3730ca10..3b61b0ccc35 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplaceNodeCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplaceNodeCmd.java
@@ -47,7 +47,12 @@ public void call(AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList
     ZkStateReader zkStateReader = ccc.getZkStateReader();
     String source = message.getStr(CollectionParams.SOURCE_NODE);
     String target = message.getStr(CollectionParams.TARGET_NODE);
-    boolean waitForFinalState = message.getBool(CommonAdminParams.WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP,
+            false);
     if (source == null) {
       throw new SolrException(
           SolrException.ErrorCode.BAD_REQUEST, "sourceNode is a required param");
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplicaMigrationUtils.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplicaMigrationUtils.java
index be08e6fc573..79ee6677d84 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplicaMigrationUtils.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/ReplicaMigrationUtils.java
@@ -35,6 +35,7 @@
 import org.apache.solr.common.cloud.ZkNodeProps;
 import org.apache.solr.common.cloud.ZkStateReader;
 import org.apache.solr.common.params.CollectionParams;
+import org.apache.solr.common.params.CommonAdminParams;
 import org.apache.solr.common.params.CoreAdminParams;
 import org.apache.solr.common.util.NamedList;
 import org.apache.zookeeper.KeeperException;
@@ -106,7 +107,10 @@ static boolean migrateReplicas(
           sourceReplica
               .toFullProps()
               .plus("parallel", String.valueOf(parallel))
-              .plus(CoreAdminParams.NODE, targetNode);
+              .plus(CoreAdminParams.NODE, targetNode)
+              // this method has its own watcher/latch below, conditioned on waitForFinalState;
+              // don't let AddReplicaCmd's own wait run (and block on) first.
+              .plus(CommonAdminParams.WAIT_FOR_FINAL_STATE, "false");
       NamedList<Object> nl = new NamedList<>();
       final ZkNodeProps addedReplica =
           new AddReplicaCmd(ccc)
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/RestoreCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/RestoreCmd.java
index dabaf64420e..89e1d3f3628 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/RestoreCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/RestoreCmd.java
@@ -65,6 +65,7 @@
 import org.apache.solr.common.cloud.ZkStateReader;
 import org.apache.solr.common.params.CollectionAdminParams;
 import org.apache.solr.common.params.CollectionParams;
+import org.apache.solr.common.params.CommonAdminParams;
 import org.apache.solr.common.params.CoreAdminParams;
 import org.apache.solr.common.params.ModifiableSolrParams;
 import org.apache.solr.common.util.CollectionUtil;
@@ -358,6 +359,9 @@ private void createCoreLessCollection(
       propMap.put(
           CollectionHandlingUtils.CREATE_NODE_SET,
           CollectionHandlingUtils.CREATE_NODE_SET_EMPTY); // no cores
+      // no cores are created here (see above), but keep this call's contract independent of the
+      // operator-configurable default regardless -- restore does its own waiting elsewhere.
+      propMap.put(CommonAdminParams.WAIT_FOR_FINAL_STATE, "false");
       propMap.put(CollectionAdminParams.COLL_CONF, restoreConfigName);
 
       // router.*
@@ -452,6 +456,9 @@ private void createSingleReplicaPerShard(
         propMap.put(COLLECTION_PROP, restoreCollection.getName());
         propMap.put(SHARD_ID_PROP, sliceName);
         propMap.put(REPLICA_TYPE, numReplicas.getLeaderType().name());
+        // the onComplete callback below drives this method's own countDownLatch; don't let
+        // AddReplicaCmd's own wait run (and block on) first.
+        propMap.put(CommonAdminParams.WAIT_FOR_FINAL_STATE, "false");
 
         // Get the first node matching the shard to restore in
         String node;
@@ -567,6 +574,9 @@ private void addReplicasToShards(
             propMap.put(COLLECTION_PROP, restoreCollection.getName());
             propMap.put(SHARD_ID_PROP, slice.getName());
             propMap.put(REPLICA_TYPE, typeToCreate.name());
+            // restore does its own waiting elsewhere; don't let AddReplicaCmd's own wait
+            // (bounded by its default 10-minute timeout, per shard) run here instead.
+            propMap.put(CommonAdminParams.WAIT_FOR_FINAL_STATE, "false");
 
             // Get the first node matching the shard to restore in
             String node;
diff --git a/solr/core/src/java/org/apache/solr/cloud/api/collections/SplitShardCmd.java b/solr/core/src/java/org/apache/solr/cloud/api/collections/SplitShardCmd.java
index 6740c5ba046..5f008251421 100644
--- a/solr/core/src/java/org/apache/solr/cloud/api/collections/SplitShardCmd.java
+++ b/solr/core/src/java/org/apache/solr/cloud/api/collections/SplitShardCmd.java
@@ -136,7 +136,12 @@ public void call(AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList
   public boolean split(
       AdminCmdContext adminCmdContext, ZkNodeProps message, NamedList<Object> results)
       throws Exception {
-    boolean waitForFinalState = message.getBool(CommonAdminParams.WAIT_FOR_FINAL_STATE, false);
+    boolean waitForFinalState =
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            message,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE,
+            CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP,
+            true);
     String methodStr =
         message.getStr(
             CommonAdminParams.SPLIT_METHOD, SolrIndexSplitter.SplitMethod.REWRITE.toLower());
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java b/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
index 270afc24906..fabd30e31b2 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/CollectionsHandler.java
@@ -1164,7 +1164,6 @@ public Map<String, Object> execute(
           final RequiredSolrParams requiredParams = req.getParams().required();
           final var requestBody = new ReplaceNodeRequestBody();
           requestBody.targetNodeName = params.get(TARGET_NODE);
-          requestBody.waitForFinalState = params.getBool(WAIT_FOR_FINAL_STATE);
           requestBody.async = params.get(ASYNC);
           final ReplaceNode replaceNodeAPI = new ReplaceNode(h.coreContainer, req, rsp);
           final SolrJerseyResponse replaceNodeResponse =
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/api/BalanceReplicas.java b/solr/core/src/java/org/apache/solr/handler/admin/api/BalanceReplicas.java
index 8ee0a7e4e77..b95f9aa7908 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/api/BalanceReplicas.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/api/BalanceReplicas.java
@@ -17,7 +17,6 @@
 package org.apache.solr.handler.admin.api;
 
 import static org.apache.solr.common.params.CollectionParams.NODES;
-import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE;
 import static org.apache.solr.security.PermissionNameProvider.Name.COLL_EDIT_PERM;
 
 import jakarta.inject.Inject;
@@ -65,7 +64,6 @@ public ZkNodeProps createRemoteMessage(BalanceReplicasRequestBody requestBody) {
     final Map<String, Object> remoteMessage = new HashMap<>();
     if (requestBody != null) {
       insertIfNotNull(remoteMessage, NODES, requestBody.nodes);
-      insertIfNotNull(remoteMessage, WAIT_FOR_FINAL_STATE, requestBody.waitForFinalState);
     }
 
     return new ZkNodeProps(remoteMessage);
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/api/MigrateReplicas.java b/solr/core/src/java/org/apache/solr/handler/admin/api/MigrateReplicas.java
index ad9b9604080..90c55c299f1 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/api/MigrateReplicas.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/api/MigrateReplicas.java
@@ -18,7 +18,6 @@
 
 import static org.apache.solr.common.params.CollectionParams.SOURCE_NODES;
 import static org.apache.solr.common.params.CollectionParams.TARGET_NODES;
-import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE;
 import static org.apache.solr.security.PermissionNameProvider.Name.COLL_EDIT_PERM;
 
 import jakarta.inject.Inject;
@@ -73,7 +72,6 @@ public ZkNodeProps createRemoteMessage(MigrateReplicasRequestBody requestBody) {
       }
       insertIfNotNull(remoteMessage, SOURCE_NODES, requestBody.sourceNodes);
       insertIfNotNull(remoteMessage, TARGET_NODES, requestBody.targetNodes);
-      insertIfNotNull(remoteMessage, WAIT_FOR_FINAL_STATE, requestBody.waitForFinalState);
     } else {
       throw new SolrException(
           SolrException.ErrorCode.BAD_REQUEST,
diff --git a/solr/core/src/java/org/apache/solr/handler/admin/api/ReplaceNode.java b/solr/core/src/java/org/apache/solr/handler/admin/api/ReplaceNode.java
index cd162659087..f2f20455235 100644
--- a/solr/core/src/java/org/apache/solr/handler/admin/api/ReplaceNode.java
+++ b/solr/core/src/java/org/apache/solr/handler/admin/api/ReplaceNode.java
@@ -18,7 +18,6 @@
 
 import static org.apache.solr.common.params.CollectionParams.SOURCE_NODE;
 import static org.apache.solr.common.params.CollectionParams.TARGET_NODE;
-import static org.apache.solr.common.params.CommonAdminParams.WAIT_FOR_FINAL_STATE;
 import static org.apache.solr.security.PermissionNameProvider.Name.COLL_EDIT_PERM;
 
 import jakarta.inject.Inject;
@@ -71,7 +70,6 @@ public ZkNodeProps createRemoteMessage(String nodeName, ReplaceNodeRequestBody r
     remoteMessage.put(SOURCE_NODE, nodeName);
     if (requestBody != null) {
       insertIfValueNotNull(remoteMessage, TARGET_NODE, requestBody.targetNodeName);
-      insertIfValueNotNull(remoteMessage, WAIT_FOR_FINAL_STATE, requestBody.waitForFinalState);
     }
 
     return new ZkNodeProps(remoteMessage);
diff --git a/solr/core/src/test/org/apache/solr/cloud/AddReplicaTest.java b/solr/core/src/test/org/apache/solr/cloud/AddReplicaTest.java
index 8c0750635ca..67fe7bd0759 100644
--- a/solr/core/src/test/org/apache/solr/cloud/AddReplicaTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/AddReplicaTest.java
@@ -155,8 +155,6 @@ public void test() throws Exception {
     replicas2.removeAll(replicas);
     assertEquals(1, replicas2.size());
 
-    // use waitForFinalState
-    addReplica.setWaitForFinalState(true);
     addReplica.processAsync("001", cloudClient);
     requestStatus = CollectionAdminRequest.requestStatus("001");
     rsp = requestStatus.process(cloudClient);
@@ -205,7 +203,6 @@ public void testAddReplicaWithUserDefinedProperties() throws Exception {
         CollectionAdminRequest.addReplicaToShard(collectionName, "shard1");
     addReplica.withProperty("customProp2", "val2.1");
     addReplica.withProperty("customProp3", "val3");
-    addReplica.setWaitForFinalState(true);
     addReplica.process(cloudClient);
 
     // Verify that the new core was created with user-defined properties coming from the request
diff --git a/solr/core/src/test/org/apache/solr/cloud/BalanceReplicasTest.java b/solr/core/src/test/org/apache/solr/cloud/BalanceReplicasTest.java
index 79a8a80e0a4..96290c421ef 100644
--- a/solr/core/src/test/org/apache/solr/cloud/BalanceReplicasTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/BalanceReplicasTest.java
@@ -140,7 +140,14 @@ public void testSomeNodes() throws Exception {
     postDataAndGetResponse(
         "/api/cluster/replicas/balance",
         Utils.getReflectWriter(
-            new BalanceReplicasRequestBody(new HashSet<>(l.subList(1, 4)), true, null)));
+            new BalanceReplicasRequestBody(new HashSet<>(l.subList(1, 4)), null)));
+
+    waitForState(
+        "Timed out waiting for replicas to be balanced across the target nodes",
+        coll,
+        (state) ->
+            state.replicaStream().map(Replica::getNodeName).collect(Collectors.toSet()).size()
+                == 4);
 
     collection = cloudClient.getClusterState().getCollectionOrNull(coll, false);
     log.debug("### After balancing: {}", collection);
diff --git a/solr/core/src/test/org/apache/solr/cloud/CollectionsAPISolrJTest.java b/solr/core/src/test/org/apache/solr/cloud/CollectionsAPISolrJTest.java
index 44c24de9b10..846f5c28c77 100644
--- a/solr/core/src/test/org/apache/solr/cloud/CollectionsAPISolrJTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/CollectionsAPISolrJTest.java
@@ -232,7 +232,6 @@ public void testCreateAndDeleteCollection() throws Exception {
     String collectionName = getSaferTestName();
     CollectionAdminRequest.Create createREq =
         CollectionAdminRequest.createCollection(collectionName, "conf", 2, 2);
-    createREq.setWaitForFinalState(false);
     CollectionAdminResponse response = createREq.process(cluster.getSolrClient());
 
     assertEquals(0, response.getStatus());
diff --git a/solr/core/src/test/org/apache/solr/cloud/MigrateReplicasTest.java b/solr/core/src/test/org/apache/solr/cloud/MigrateReplicasTest.java
index 1d4d431d6df..fc5291daafb 100644
--- a/solr/core/src/test/org/apache/solr/cloud/MigrateReplicasTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/MigrateReplicasTest.java
@@ -117,11 +117,15 @@ public void test() throws Exception {
     Map<?, ?> response =
         callMigrateReplicas(
             new MigrateReplicasRequestBody(
-                Set.of(nodeToBeDecommissioned), Set.of(emptyNode), true, null));
+                Set.of(nodeToBeDecommissioned), Set.of(emptyNode), null));
     assertEquals(
         "MigrateReplicas request was unsuccessful",
         0L,
         ((Map<?, ?>) response.get("responseHeader")).get("status"));
+    waitForState(
+        "Timed out waiting for replicas to be migrated off the decommissioned node",
+        coll,
+        (state) -> state.getReplicasOnNode(nodeToBeDecommissioned).isEmpty());
     ZkStateReader zkStateReader = ZkStateReader.from(cloudClient);
     try (SolrClient coreClient =
         getHttpSolrClient(zkStateReader.getBaseUrlForNodeName(nodeToBeDecommissioned))) {
@@ -144,11 +148,18 @@ public void test() throws Exception {
     response =
         callMigrateReplicas(
             new MigrateReplicasRequestBody(
-                Set.of(emptyNode), Set.of(nodeToBeDecommissioned), true, null));
+                Set.of(emptyNode), Set.of(nodeToBeDecommissioned), null));
     assertEquals(
         "MigrateReplicas request was unsuccessful",
         0L,
         ((Map<?, ?>) response.get("responseHeader")).get("status"));
+    waitForState(
+        "Timed out waiting for replicas to be migrated back off the empty node and become active",
+        coll,
+        (state) ->
+            state.getReplicasOnNode(emptyNode).isEmpty()
+                && state.getReplicasOnNode(nodeToBeDecommissioned).stream()
+                    .allMatch(r -> r.getState() == Replica.State.ACTIVE));
 
     try (SolrClient coreClient =
         getHttpSolrClient(zkStateReader.getBaseUrlForNodeName(emptyNode))) {
@@ -250,12 +261,17 @@ public void testWithNoTarget() throws Exception {
     log.info("### Before decommission: {}", initialCollection);
     Map<?, ?> response =
         callMigrateReplicas(
-            new MigrateReplicasRequestBody(
-                new HashSet<>(nodesToBeDecommissioned), Set.of(), true, null));
+            new MigrateReplicasRequestBody(new HashSet<>(nodesToBeDecommissioned), Set.of(), null));
     assertEquals(
         "MigrateReplicas request was unsuccessful",
         0L,
         ((Map<?, ?>) response.get("responseHeader")).get("status"));
+    waitForState(
+        "Timed out waiting for replicas to be migrated off the decommissioned nodes",
+        coll,
+        (state) ->
+            nodesToBeDecommissioned.stream()
+                .allMatch(node -> state.getReplicasOnNode(node).isEmpty()));
 
     DocCollection collection = cloudClient.getClusterState().getCollectionOrNull(coll, false);
     assertNotNull("Collection cannot be null: " + coll, collection);
@@ -294,7 +310,7 @@ public void testFailOnSingleNode() throws Exception {
 
     String liveNode = cloudClient.getClusterState().getLiveNodes().iterator().next();
     Map<?, ?> response =
-        callMigrateReplicas(new MigrateReplicasRequestBody(Set.of(liveNode), Set.of(), true, null));
+        callMigrateReplicas(new MigrateReplicasRequestBody(Set.of(liveNode), Set.of(), null));
     assertNotNull(
         "No error in response, when the request should have failed", response.get("error"));
     assertEquals(
diff --git a/solr/core/src/test/org/apache/solr/cloud/ReplaceNodeTest.java b/solr/core/src/test/org/apache/solr/cloud/ReplaceNodeTest.java
index bc64635d2d8..a7dd392c9b6 100644
--- a/solr/core/src/test/org/apache/solr/cloud/ReplaceNodeTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/ReplaceNodeTest.java
@@ -133,7 +133,6 @@ public void test() throws Exception {
     // let's do it back - this time wait for recoveries
     CollectionAdminRequest.AsyncCollectionAdminRequest replaceNodeRequest =
         createReplaceNodeRequest(emptyNode, nodeToBeDecommissioned, Boolean.TRUE);
-    replaceNodeRequest.setWaitForFinalState(true);
     replaceNodeRequest.processAndWait("001", cloudClient, 10);
 
     try (SolrClient coreClient =
diff --git a/solr/core/src/test/org/apache/solr/cloud/SplitShardTest.java b/solr/core/src/test/org/apache/solr/cloud/SplitShardTest.java
index 0b539bd39d0..7729183cb26 100644
--- a/solr/core/src/test/org/apache/solr/cloud/SplitShardTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/SplitShardTest.java
@@ -192,7 +192,6 @@ public void testWithChildDocuments() throws Exception {
         CollectionAdminRequest.splitShard(COLLECTION_NAME)
             .setNumSubShards(2)
             .setShardName("shard1");
-    splitShard.setWaitForFinalState(true);
     splitShard.process(solrClient);
     waitForState(
         "Waiting for 2 active shards after split", COLLECTION_NAME, activeClusterShape(2, 2));
diff --git a/solr/core/src/test/org/apache/solr/cloud/SplitShardWithNodeRoleTest.java b/solr/core/src/test/org/apache/solr/cloud/SplitShardWithNodeRoleTest.java
index eb15bd44420..9530bb34ca0 100644
--- a/solr/core/src/test/org/apache/solr/cloud/SplitShardWithNodeRoleTest.java
+++ b/solr/core/src/test/org/apache/solr/cloud/SplitShardWithNodeRoleTest.java
@@ -21,8 +21,15 @@
 import java.util.Set;
 import org.apache.solr.client.solrj.impl.CloudSolrClient;
 import org.apache.solr.client.solrj.request.CollectionAdminRequest;
+import org.apache.solr.client.solrj.request.CollectionAdminRequest.AsyncCollectionAdminRequest;
 import org.apache.solr.client.solrj.request.UpdateRequest;
 import org.apache.solr.common.SolrInputDocument;
+import org.apache.solr.common.params.CollectionAdminParams;
+import org.apache.solr.common.params.CollectionParams.CollectionAction;
+import org.apache.solr.common.params.CommonAdminParams;
+import org.apache.solr.common.params.CoreAdminParams;
+import org.apache.solr.common.params.ModifiableSolrParams;
+import org.apache.solr.common.params.SolrParams;
 import org.apache.solr.core.NodeRoles;
 import org.apache.solr.util.LogLevel;
 import org.junit.BeforeClass;
@@ -85,10 +92,20 @@ public void doSplit(String collName, int shard, int nrtReplica, int pullReplica)
     ur.commit(client, collName);
 
     final int numSubShards = 2;
-    CollectionAdminRequest.SplitShard splitShard =
-        CollectionAdminRequest.splitShard(collName)
-            .setShardName("shard1")
-            .setNumSubShards(numSubShards);
+    // this method does its own explicit waitForState(...) below; pin waitForFinalState=false
+    // so SPLITSHARD's own new default doesn't also wait (and risk the client's HTTP timeout).
+    AsyncCollectionAdminRequest splitShard =
+        new AsyncCollectionAdminRequest(CollectionAction.SPLITSHARD) {
+          @Override
+          public SolrParams getParams() {
+            ModifiableSolrParams params = (ModifiableSolrParams) super.getParams();
+            params.set(CollectionAdminParams.COLLECTION, collName);
+            params.set(CoreAdminParams.SHARD, "shard1");
+            params.set("numSubShards", numSubShards);
+            params.set(CommonAdminParams.WAIT_FOR_FINAL_STATE, false);
+            return params;
+          }
+        };
     splitShard.process(cluster.getSolrClient());
     int totalShards = shard + (numSubShards - 1);
     waitForState(
diff --git a/solr/core/src/test/org/apache/solr/cloud/api/collections/CollectionHandlingUtilsTest.java b/solr/core/src/test/org/apache/solr/cloud/api/collections/CollectionHandlingUtilsTest.java
new file mode 100644
index 00000000000..ee99621b235
--- /dev/null
+++ b/solr/core/src/test/org/apache/solr/cloud/api/collections/CollectionHandlingUtilsTest.java
@@ -0,0 +1,73 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.cloud.api.collections;
+
+import java.util.Map;
+import org.apache.solr.SolrTestCase;
+import org.apache.solr.common.cloud.ZkNodeProps;
+import org.junit.After;
+import org.junit.Test;
+
+public class CollectionHandlingUtilsTest extends SolrTestCase {
+
+  private static final String MESSAGE_PARAM = "waitForFinalState";
+  private static final String ENV_PROP = "solr.cloud.waitForFinalStateEnvFallbackTest.enabled";
+
+  @After
+  public void clearProperty() {
+    System.clearProperty(ENV_PROP);
+  }
+
+  @Test
+  public void testMessageUnsetEnvUnsetFallsBackToDefault() {
+    ZkNodeProps message = new ZkNodeProps(Map.of());
+    assertTrue(
+        CollectionHandlingUtils.getBoolWithEnvFallback(message, MESSAGE_PARAM, ENV_PROP, true));
+    assertFalse(
+        CollectionHandlingUtils.getBoolWithEnvFallback(message, MESSAGE_PARAM, ENV_PROP, false));
+  }
+
+  @Test
+  public void testMessageUnsetEnvSetFalseOverridesDefaultTrue() {
+    System.setProperty(ENV_PROP, "false");
+    ZkNodeProps message = new ZkNodeProps(Map.of());
+    assertFalse(
+        CollectionHandlingUtils.getBoolWithEnvFallback(message, MESSAGE_PARAM, ENV_PROP, true));
+  }
+
+  @Test
+  public void testMessageUnsetEnvSetTrueOverridesDefaultFalse() {
+    System.setProperty(ENV_PROP, "true");
+    ZkNodeProps message = new ZkNodeProps(Map.of());
+    assertTrue(
+        CollectionHandlingUtils.getBoolWithEnvFallback(message, MESSAGE_PARAM, ENV_PROP, false));
+  }
+
+  @Test
+  public void testExplicitMessageParamWinsOverEnvFallback() {
+    System.setProperty(ENV_PROP, "true");
+    ZkNodeProps messageFalse = new ZkNodeProps(Map.of(MESSAGE_PARAM, "false"));
+    assertFalse(
+        CollectionHandlingUtils.getBoolWithEnvFallback(
+            messageFalse, MESSAGE_PARAM, ENV_PROP, false));
+
+    System.setProperty(ENV_PROP, "false");
+    ZkNodeProps messageTrue = new ZkNodeProps(Map.of(MESSAGE_PARAM, "true"));
+    assertTrue(
+        CollectionHandlingUtils.getBoolWithEnvFallback(messageTrue, MESSAGE_PARAM, ENV_PROP, true));
+  }
+}
diff --git a/solr/core/src/test/org/apache/solr/cloud/api/collections/WaitForFinalStateEnvFallbackTest.java b/solr/core/src/test/org/apache/solr/cloud/api/collections/WaitForFinalStateEnvFallbackTest.java
new file mode 100644
index 00000000000..a86652cad90
--- /dev/null
+++ b/solr/core/src/test/org/apache/solr/cloud/api/collections/WaitForFinalStateEnvFallbackTest.java
@@ -0,0 +1,131 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.cloud.api.collections;
+
+import java.lang.invoke.MethodHandles;
+import org.apache.solr.client.solrj.SolrClient;
+import org.apache.solr.client.solrj.request.CollectionAdminRequest;
+import org.apache.solr.client.solrj.request.CollectionAdminRequest.AsyncCollectionAdminRequest;
+import org.apache.solr.cloud.SolrCloudTestCase;
+import org.apache.solr.common.cloud.DocCollection;
+import org.apache.solr.common.cloud.Replica;
+import org.apache.solr.common.params.CollectionParams.CollectionAction;
+import org.apache.solr.common.params.CommonAdminParams;
+import org.apache.solr.common.params.CoreAdminParams;
+import org.apache.solr.common.params.ModifiableSolrParams;
+import org.apache.solr.common.params.SolrParams;
+import org.apache.solr.util.TestInjection;
+import org.junit.After;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class WaitForFinalStateEnvFallbackTest extends SolrCloudTestCase {
+  private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
+
+  @BeforeClass
+  public static void setupCluster() throws Exception {
+    configureCluster(2).addConfig("conf", configset("cloud-minimal")).configure();
+  }
+
+  @After
+  public void releaseInjectionAndProperty() {
+    TestInjection.prepRecoveryOpPauseForever = null;
+    TestInjection.notifyPauseForeverDone();
+    System.clearProperty(CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP);
+  }
+
+  private static AsyncCollectionAdminRequest addReplicaWithTimeout(
+      String collection, String shard, int timeoutSeconds) {
+    return new AsyncCollectionAdminRequest(CollectionAction.ADDREPLICA) {
+      @Override
+      public SolrParams getParams() {
+        ModifiableSolrParams params = (ModifiableSolrParams) super.getParams();
+        params.set(CoreAdminParams.COLLECTION, collection);
+        params.set(CoreAdminParams.SHARD, shard);
+        params.set(CommonAdminParams.TIMEOUT, timeoutSeconds);
+        return params;
+      }
+    };
+  }
+
+  @Test
+  public void testDefaultFalseSkipsWaitEvenWhenRecoveryIsStuck() throws Exception {
+    String collection = "envfallbackfalse";
+    SolrClient client = cluster.getSolrClient();
+    CollectionAdminRequest.createCollection(collection, "conf", 1, 1).process(client);
+    cluster.waitForActiveCollection(collection, 1, 1);
+
+    // no system property set: ADDREPLICA's literal default is false (waiting on a replica's
+    // recovery is unbounded in time, unlike CREATE/CREATESHARD/SPLITSHARD's brand-new replicas)
+    TestInjection.prepRecoveryOpPauseForever = "true:100";
+
+    long start = System.nanoTime();
+    addReplicaWithTimeout(collection, "shard1", 5).process(client);
+    long elapsedMs = (System.nanoTime() - start) / 1_000_000;
+    log.info("ADDREPLICA with default (false) returned after {}ms", elapsedMs);
+
+    // proves we returned without waiting on the (permanently stuck) recovery: if the
+    // ActiveReplicaWatcher had been registered with the 5s timeout above, a genuine wait would
+    // either finish fast (if it wasn't really stuck) or throw after ~5s -- neither of which we
+    // want; we want no watcher registered at all, so this returns near-instantly.
+    assertTrue(
+        "expected ADDREPLICA to return promptly since waitForFinalState defaults to false, "
+            + "but it took "
+            + elapsedMs
+            + "ms",
+        elapsedMs < 5_000);
+
+    DocCollection coll = cluster.getSolrClient().getClusterState().getCollection(collection);
+    boolean anyNonActive = coll.replicaStream().anyMatch(r -> r.getState() != Replica.State.ACTIVE);
+    assertTrue(
+        "expected the new replica to still be stuck in recovery (not ACTIVE) since we "
+            + "returned before waiting for final state",
+        anyNonActive);
+  }
+
+  @Test
+  public void testEnvFallbackTrueActuallyWaitsAndTimesOutWhenRecoveryIsStuck() throws Exception {
+    String collection = "envfallbacktrue";
+    SolrClient client = cluster.getSolrClient();
+    CollectionAdminRequest.createCollection(collection, "conf", 1, 1).process(client);
+    cluster.waitForActiveCollection(collection, 1, 1);
+
+    System.setProperty(CommonAdminParams.WAIT_FOR_FINAL_STATE_DEFAULT_PROP, "true");
+    TestInjection.prepRecoveryOpPauseForever = "true:100";
+
+    long start = System.nanoTime();
+    boolean threw = false;
+    try {
+      addReplicaWithTimeout(collection, "shard1", 5).process(client);
+    } catch (Exception e) {
+      threw = true;
+      log.info("ADDREPLICA with env fallback=true threw as expected: {}", e);
+    }
+    long elapsedMs = (System.nanoTime() - start) / 1_000_000;
+    log.info("ADDREPLICA with env fallback=true returned/threw after {}ms", elapsedMs);
+
+    assertTrue(
+        "expected ADDREPLICA to actually wait for final state (and time out, since recovery "
+            + "is permanently stuck) when waitForFinalState resolves to true via the env "
+            + "fallback, but it returned successfully after only "
+            + elapsedMs
+            + "ms",
+        threw);
+  }
+}
diff --git a/solr/core/src/test/org/apache/solr/core/TestSetPropertyConfigApis.java b/solr/core/src/test/org/apache/solr/core/TestSetPropertyConfigApis.java
index 54c30f7d75f..8bf024cbecd 100644
--- a/solr/core/src/test/org/apache/solr/core/TestSetPropertyConfigApis.java
+++ b/solr/core/src/test/org/apache/solr/core/TestSetPropertyConfigApis.java
@@ -279,7 +279,6 @@ public void testTwoCollectionsWithDifferentProps() throws Exception {
 
   private static void processAndAssertSuccess(final CollectionAdminRequest.Create op)
       throws Exception {
-    op.setWaitForFinalState(true);
     assertTrue(op.process(cluster.getSolrClient()).isSuccess());
   }
 
diff --git a/solr/core/src/test/org/apache/solr/handler/admin/api/MigrateReplicasAPITest.java b/solr/core/src/test/org/apache/solr/handler/admin/api/MigrateReplicasAPITest.java
index 574d671f595..5c901f1c5de 100644
--- a/solr/core/src/test/org/apache/solr/handler/admin/api/MigrateReplicasAPITest.java
+++ b/solr/core/src/test/org/apache/solr/handler/admin/api/MigrateReplicasAPITest.java
@@ -42,8 +42,7 @@ public void setUp() throws Exception {
   @Test
   public void testCreatesValidOverseerMessage() throws Exception {
     MigrateReplicasRequestBody requestBody =
-        new MigrateReplicasRequestBody(
-            Set.of("demoSourceNode"), Set.of("demoTargetNode"), false, "async");
+        new MigrateReplicasRequestBody(Set.of("demoSourceNode"), Set.of("demoTargetNode"), "async");
 
     api.migrateReplicas(requestBody);
 
@@ -51,17 +50,16 @@ public void testCreatesValidOverseerMessage() throws Exception {
         CollectionParams.CollectionAction.MIGRATE_REPLICAS,
         "async",
         message -> {
-          assertEquals(3, message.size());
+          assertEquals(2, message.size());
           assertEquals(Set.of("demoSourceNode"), message.get("sourceNodes"));
           assertEquals(Set.of("demoTargetNode"), message.get("targetNodes"));
-          assertEquals(false, message.get("waitForFinalState"));
         });
   }
 
   @Test
   public void testNoTargetNodes() throws Exception {
     MigrateReplicasRequestBody requestBody =
-        new MigrateReplicasRequestBody(Set.of("demoSourceNode"), null, null, null);
+        new MigrateReplicasRequestBody(Set.of("demoSourceNode"), null, null);
 
     api.migrateReplicas(requestBody);
 
@@ -76,10 +74,10 @@ public void testNoTargetNodes() throws Exception {
   @Test
   public void testNoSourceNodesThrowsError() {
     MigrateReplicasRequestBody requestBody1 =
-        new MigrateReplicasRequestBody(Set.of(), Set.of("demoTargetNode"), null, null);
+        new MigrateReplicasRequestBody(Set.of(), Set.of("demoTargetNode"), null);
     assertThrows(SolrException.class, () -> api.migrateReplicas(requestBody1));
     MigrateReplicasRequestBody requestBody2 =
-        new MigrateReplicasRequestBody(null, Set.of("demoTargetNode"), null, null);
+        new MigrateReplicasRequestBody(null, Set.of("demoTargetNode"), null);
     assertThrows(SolrException.class, () -> api.migrateReplicas(requestBody2));
   }
 }
diff --git a/solr/core/src/test/org/apache/solr/handler/admin/api/ReplaceNodeAPITest.java b/solr/core/src/test/org/apache/solr/handler/admin/api/ReplaceNodeAPITest.java
index 7386c4e2967..2fcfda81f2c 100644
--- a/solr/core/src/test/org/apache/solr/handler/admin/api/ReplaceNodeAPITest.java
+++ b/solr/core/src/test/org/apache/solr/handler/admin/api/ReplaceNodeAPITest.java
@@ -39,7 +39,7 @@ public void setUp() throws Exception {
 
   @Test
   public void testCreatesValidOverseerMessage() throws Exception {
-    final var requestBody = new ReplaceNodeRequestBody("demoTargetNode", false, "async");
+    final var requestBody = new ReplaceNodeRequestBody("demoTargetNode", "async");
 
     api.replaceNode("demoSourceNode", requestBody);
 
@@ -47,10 +47,9 @@ public void testCreatesValidOverseerMessage() throws Exception {
         CollectionParams.CollectionAction.REPLACENODE,
         requestBody.async,
         message -> {
-          assertEquals(3, message.size());
+          assertEquals(2, message.size());
           assertEquals("demoSourceNode", message.get("sourceNode"));
           assertEquals("demoTargetNode", message.get("targetNode"));
-          assertEquals(false, message.get("waitForFinalState"));
         });
   }
 
@@ -68,7 +67,7 @@ public void testRequestBodyCanBeOmittedAltogether() throws Exception {
 
   @Test
   public void testOptionalValuesNotAddedToRemoteMessageIfNotProvided() throws Exception {
-    final var requestBody = new ReplaceNodeRequestBody("demoTargetNode", null, null);
+    final var requestBody = new ReplaceNodeRequestBody("demoTargetNode", null);
 
     api.replaceNode("demoSourceNode", requestBody);
 
@@ -78,10 +77,6 @@ public void testOptionalValuesNotAddedToRemoteMessageIfNotProvided() throws Exce
           assertEquals(2, message.size());
           assertEquals("demoSourceNode", message.get("sourceNode"));
           assertEquals("demoTargetNode", message.get("targetNode"));
-          assertFalse(
-              "Expected message to not contain value for waitForFinalState: "
-                  + message.get("waitForFinalState"),
-              message.containsKey("waitForFinalState"));
         });
   }
 }
diff --git a/solr/core/src/test/org/apache/solr/handler/admin/api/WaitForFinalStateRequestBodyOmittedFieldTest.java b/solr/core/src/test/org/apache/solr/handler/admin/api/WaitForFinalStateRequestBodyOmittedFieldTest.java
new file mode 100644
index 00000000000..4a9ae8edc46
--- /dev/null
+++ b/solr/core/src/test/org/apache/solr/handler/admin/api/WaitForFinalStateRequestBodyOmittedFieldTest.java
@@ -0,0 +1,43 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.solr.handler.admin.api;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.solr.SolrTestCase;
+import org.apache.solr.client.api.model.CreateCollectionRequestBody;
+import org.apache.solr.client.api.model.CreateReplicaRequestBody;
+import org.apache.solr.client.api.model.CreateShardRequestBody;
+import org.junit.Test;
+
+/**
+ * AC8 (SOLR-18367): a v2 REST request body that omits {@code waitForFinalState} must deserialize to
+ * {@code null}, not {@code false}, so {@code insertIfNotNull} lets the server's own EnvUtils-driven
+ * default apply -- the same as SolrJ's field-omitted case. Only applies to the bounded commands
+ * (CREATE, CREATESHARD, ADDREPLICA); BALANCE_REPLICAS/MIGRATE_REPLICAS/ REPLACENODE dropped the
+ * field entirely -- their default stays `false` unconditionally.
+ */
+public class WaitForFinalStateRequestBodyOmittedFieldTest extends SolrTestCase {
+
+  private final ObjectMapper mapper = new ObjectMapper();
+
+  @Test
+  public void testOmittedFieldDeserializesToNullNotFalse() throws Exception {
+    assertNull(mapper.readValue("{}", CreateCollectionRequestBody.class).waitForFinalState);
+    assertNull(mapper.readValue("{}", CreateShardRequestBody.class).waitForFinalState);
+    assertNull(mapper.readValue("{}", CreateReplicaRequestBody.class).waitForFinalState);
+  }
+}
diff --git a/solr/solr-ref-guide/modules/deployment-guide/pages/cluster-node-management.adoc b/solr/solr-ref-guide/modules/deployment-guide/pages/cluster-node-management.adoc
index 46517de459d..c5bd4ea7326 100644
--- a/solr/solr-ref-guide/modules/deployment-guide/pages/cluster-node-management.adoc
+++ b/solr/solr-ref-guide/modules/deployment-guide/pages/cluster-node-management.adoc
@@ -535,6 +535,7 @@ If this parameter is not provided, all live data nodes will be used.
 +
 If `true`, the request will complete only when all affected replicas become active.
 If `false`, the API will return when the bare minimum replicas are active, such as the affected leader replicas.
+This command can affect an arbitrary number of replicas cluster-wide, so unlike other Collections API commands it keeps the pre-SOLR-18367 default; an operator can opt in cluster-wide without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=true` on each Solr node.
 
 `async`::
 +
@@ -724,6 +725,7 @@ If there is more than one node to migrate the replicas to, then the configured P
 +
 If `true`, the request will complete only when all affected replicas become active.
 If `false`, the API will return when the bare minimum replicas are active, such as the affected leader replicas.
+This command can affect an arbitrary number of replicas cluster-wide, so unlike other Collections API commands it keeps the pre-SOLR-18367 default; an operator can opt in cluster-wide without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=true` on each Solr node.
 
 `async`::
 +
@@ -783,7 +785,6 @@ V2 API::
 curl -X POST "http://localhost:8983/api/cluster/nodes/localhost:7574_solr/replace" -H 'Content-Type: application/json' -d '
     {
       "targetNodeName": "localhost:8983_solr",
-      "waitForFinalState": "false",
       "async": "async"
     }
 '
@@ -833,6 +834,7 @@ Keep in mind that this can lead to very high network and disk I/O if the replica
 +
 If `true`, the request will complete only when all affected replicas become active.
 If `false`, the API will return when the bare minimum replicas are active, such as the affected leader replicas.
+This command can affect an arbitrary number of replicas cluster-wide, so unlike other Collections API commands it keeps the pre-SOLR-18367 default; an operator can opt in cluster-wide without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=true` on each Solr node.
 
 `async`::
 +
diff --git a/solr/solr-ref-guide/modules/deployment-guide/pages/collection-management.adoc b/solr/solr-ref-guide/modules/deployment-guide/pages/collection-management.adoc
index 46452619f7c..3b45611efd0 100644
--- a/solr/solr-ref-guide/modules/deployment-guide/pages/collection-management.adoc
+++ b/solr/solr-ref-guide/modules/deployment-guide/pages/collection-management.adoc
@@ -263,11 +263,12 @@ Altering these entries by specifying `property._name_=_value_` is an expert-leve
 +
 [%autowidth,frame=none]
 |===
-|Optional |Default: none
+|Optional |Default: `true`
 |===
 +
 If `true`, the request will complete only when all affected replicas become active.
-The default is `false`, which means that the API will return the status of the single action, which may be before the new replica is online and active.
+If `false`, the API will return the status of the single action, which may be before the new replica is online and active.
+An operator can revert the cluster-wide default back to `false` without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=false` on each Solr node.
 
 `alias`::
 +
diff --git a/solr/solr-ref-guide/modules/deployment-guide/pages/replica-management.adoc b/solr/solr-ref-guide/modules/deployment-guide/pages/replica-management.adoc
index 73c19a9db47..482549151ed 100644
--- a/solr/solr-ref-guide/modules/deployment-guide/pages/replica-management.adoc
+++ b/solr/solr-ref-guide/modules/deployment-guide/pages/replica-management.adoc
@@ -239,11 +239,12 @@ Altering these entries by specifying `property._name_=_value_` is an expert-leve
 +
 [%autowidth,frame=none]
 |===
-|Optional |Default: `false`
+|Optional |Default: `true`
 |===
 +
 If `true`, the request will complete only when all affected replicas become active.
 If `false`, the API will return the status of the single action, which may be before the new replica is online and active.
+An operator can revert the cluster-wide default back to `false` without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=false` on each Solr node.
 
 `async`::
 +
diff --git a/solr/solr-ref-guide/modules/deployment-guide/pages/shard-management.adoc b/solr/solr-ref-guide/modules/deployment-guide/pages/shard-management.adoc
index e623424b6aa..6f504e9e6cc 100644
--- a/solr/solr-ref-guide/modules/deployment-guide/pages/shard-management.adoc
+++ b/solr/solr-ref-guide/modules/deployment-guide/pages/shard-management.adoc
@@ -209,11 +209,12 @@ See the section xref:configuration-guide:core-discovery.adoc[] for details on su
 +
 [%autowidth,frame=none]
 |===
-|Optional |Default: `false`
+|Optional |Default: `true`
 |===
 +
 If `true`, the request will complete only when all affected replicas become active.
 If `false`, the API will return the status of the single action, which may be before the new replica is online and active.
+An operator can revert the cluster-wide default back to `false` without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=false` on each Solr node.
 
 `timing`::
 +
@@ -423,11 +424,12 @@ See the section xref:configuration-guide:core-discovery.adoc[] for details on su
 +
 [%autowidth,frame=none]
 |===
-|Optional |Default: `false`
+|Optional |Default: `true`
 |===
 +
 If `true`, the request will complete only when all affected replicas become active.
 If `false`, the API will return the status of the single action, which may be before the new replica is online and active.
+An operator can revert the cluster-wide default back to `false` without changing any client by setting the system property `solr.cloud.waitForFinalState.enabled=false` on each Solr node.
 
 `async`::
 +
diff --git a/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java b/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
index ac7af67427c..7c0de597f33 100644
--- a/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
+++ b/solr/solrj/src/java/org/apache/solr/client/solrj/request/CollectionAdminRequest.java
@@ -146,7 +146,6 @@ public abstract static class AsyncCollectionAdminRequest
       extends CollectionAdminRequest<CollectionAdminResponse> {
 
     protected String asyncId = null;
-    protected boolean waitForFinalState = false;
 
     public AsyncCollectionAdminRequest(CollectionAction action) {
       super(action);
@@ -165,16 +164,6 @@ public String getAsyncId() {
       return asyncId;
     }
 
-    /**
-     * @deprecated Solr is moving toward always waiting for final state, with no option to opt out;
-     *     once that happens, this parameter will have no effect and will likely be removed. See
-     *     SOLR-17712.
-     */
-    @Deprecated(since = "9.10")
-    public void setWaitForFinalState(boolean waitForFinalState) {
-      this.waitForFinalState = waitForFinalState;
-    }
-
     public void setAsyncId(String asyncId) {
       this.asyncId = asyncId;
     }
@@ -242,9 +231,6 @@ public SolrParams getParams() {
       if (asyncId != null) {
         params.set(CommonAdminParams.ASYNC, asyncId);
       }
-      if (waitForFinalState) {
-        params.set(CommonAdminParams.WAIT_FOR_FINAL_STATE, waitForFinalState);
-      }
       return params;
     }
   }
diff --git a/solr/solrj/src/java/org/apache/solr/common/params/CommonAdminParams.java b/solr/solrj/src/java/org/apache/solr/common/params/CommonAdminParams.java
index b55162d01cd..e017252752d 100644
--- a/solr/solrj/src/java/org/apache/solr/common/params/CommonAdminParams.java
+++ b/solr/solrj/src/java/org/apache/solr/common/params/CommonAdminParams.java
@@ -31,6 +31,19 @@ public interface CommonAdminParams {
   @Deprecated(since = "9.10")
   String WAIT_FOR_FINAL_STATE = "waitForFinalState";
 
+  /**
+   * Node-level system property controlling the default value of {@link #WAIT_FOR_FINAL_STATE} when
+   * a request omits it. The per-command literal default it overrides differs by command: CREATE,
+   * CREATESHARD and SPLITSHARD default to {@code true} -- they only ever wait on brand-new, empty
+   * replicas, so activation is fast and bounded. ADDREPLICA, MOVEREPLICA, BALANCE_REPLICAS,
+   * MIGRATE_REPLICAS and REPLACENODE keep the pre-10.1 {@code false} default: each can wait on a
+   * replica catching up on an arbitrary amount of existing data (a full recovery/replication), so
+   * the wait is unbounded in time even when the replica count is small or fixed. Setting this
+   * property (either value) overrides the per-command default uniformly for all 8, mirroring {@code
+   * CreateCollectionCmd.PRS_DEFAULT_PROP}.
+   */
+  String WAIT_FOR_FINAL_STATE_DEFAULT_PROP = "solr.cloud.waitForFinalState.enabled";
+
   /** Allow in-place move of replicas that use shared filesystems. */
   String IN_PLACE_MOVE = "inPlaceMove";