diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
index 54f0ac030..20ffb7e3a 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/server/transport/HttpServletStatelessServerTransport.java
@@ -195,7 +195,12 @@ protected void doPost(HttpServletRequest request, HttpServletResponse response)
 
 					response.setContentType(APPLICATION_JSON);
 					response.setCharacterEncoding(UTF_8);
-					response.setStatus(HttpServletResponse.SC_OK);
+
+					int httpStatus = HttpServletResponse.SC_OK;
+					if (jsonrpcResponse.error() != null) {
+						httpStatus = mapJsonRpcErrorToHttpStatus(jsonrpcResponse.error().code());
+					}
+					response.setStatus(httpStatus);
 
 					String jsonResponseText = jsonMapper.writeValueAsString(jsonrpcResponse);
 					PrintWriter writer = response.getWriter();
@@ -249,6 +254,21 @@ else if (message instanceof McpSchema.JSONRPCNotification jsonrpcNotification) {
 		}
 	}
 
+	/**
+	 * Maps a JSON-RPC error code to an appropriate HTTP status code per the MCP
+	 * Streamable HTTP specification (2026-07-28). Only METHOD_NOT_FOUND is mapped to a
+	 * non-200 status (HTTP 404) as specified by the protocol. All other JSON-RPC errors
+	 * are returned with HTTP 200 per standard JSON-RPC conventions.
+	 * @param jsonRpcErrorCode The JSON-RPC error code
+	 * @return The corresponding HTTP status code
+	 */
+	private static int mapJsonRpcErrorToHttpStatus(int jsonRpcErrorCode) {
+		if (jsonRpcErrorCode == McpSchema.ErrorCodes.METHOD_NOT_FOUND) {
+			return HttpServletResponse.SC_NOT_FOUND;
+		}
+		return HttpServletResponse.SC_OK;
+	}
+
 	/**
 	 * Sends an error response to the client.
 	 * @param response The HTTP servlet response
diff --git a/mcp-test/src/test/java/io/modelcontextprotocol/server/HttpServletStatelessIntegrationTests.java b/mcp-test/src/test/java/io/modelcontextprotocol/server/HttpServletStatelessIntegrationTests.java
index 611175780..cd81ab951 100644
--- a/mcp-test/src/test/java/io/modelcontextprotocol/server/HttpServletStatelessIntegrationTests.java
+++ b/mcp-test/src/test/java/io/modelcontextprotocol/server/HttpServletStatelessIntegrationTests.java
@@ -915,6 +915,77 @@ public void cancel() {
 		assertThat(response.statusCode()).isEqualTo(HttpServletResponse.SC_REQUEST_ENTITY_TOO_LARGE);
 	}
 
+	@Test
+	void testMissingHandlerReturnsHttp404WithMethodNotFoundError() throws Exception {
+		var mcpServer = McpServer.sync(mcpStatelessServerTransport)
+			.serverInfo("test-server", "1.0.0")
+			.capabilities(ServerCapabilities.builder().build())
+			.build();
+
+		// Use MockHttpServletRequest/Response to directly verify the HTTP 404 status
+		// and JSON-RPC METHOD_NOT_FOUND error, since a real HTTP client treats 404
+		// as a transport-level error per the spec.
+		McpSchema.JSONRPCRequest jsonrpcRequest = new McpSchema.JSONRPCRequest("foo/bar", "test-request-123");
+
+		MockHttpServletRequest request = new MockHttpServletRequest("POST", CUSTOM_MESSAGE_ENDPOINT);
+		MockHttpServletResponse response = new MockHttpServletResponse();
+
+		byte[] content = JSON_MAPPER.writeValueAsBytes(jsonrpcRequest);
+		request.setContent(content);
+		request.addHeader("Content-Type", APPLICATION_JSON);
+		request.addHeader("Content-Length", Integer.toString(content.length));
+		request.addHeader("Accept", APPLICATION_JSON + ", " + TEXT_EVENT_STREAM);
+		request.addHeader(HttpHeaders.PROTOCOL_VERSION, ProtocolVersions.MCP_2025_03_26);
+
+		mcpStatelessServerTransport.service(request, response);
+
+		assertThat(response.getStatus()).isEqualTo(HttpServletResponse.SC_NOT_FOUND);
+
+		McpSchema.JSONRPCResponse jsonrpcResponse = JSON_MAPPER.readValue(response.getContentAsByteArray(),
+				McpSchema.JSONRPCResponse.class);
+
+		assertThat(jsonrpcResponse).isNotNull();
+		assertThat(jsonrpcResponse.error()).isNotNull();
+		assertThat(jsonrpcResponse.error().code()).isEqualTo(ErrorCodes.METHOD_NOT_FOUND);
+		assertThat(jsonrpcResponse.error().message()).isEqualTo("Method not found: foo/bar");
+
+		mcpServer.closeGracefully();
+	}
+
+	@Test
+	void testUnknownMethodReturnsHttp404WithMethodNotFoundError() throws Exception {
+		var mcpServer = McpServer.sync(mcpStatelessServerTransport)
+			.serverInfo("test-server", "1.0.0")
+			.capabilities(ServerCapabilities.builder().build())
+			.build();
+
+		McpSchema.JSONRPCRequest jsonrpcRequest = new McpSchema.JSONRPCRequest("server/discover", "discover-1");
+
+		MockHttpServletRequest request = new MockHttpServletRequest("POST", CUSTOM_MESSAGE_ENDPOINT);
+		MockHttpServletResponse response = new MockHttpServletResponse();
+
+		byte[] content = JSON_MAPPER.writeValueAsBytes(jsonrpcRequest);
+		request.setContent(content);
+		request.addHeader("Content-Type", APPLICATION_JSON);
+		request.addHeader("Content-Length", Integer.toString(content.length));
+		request.addHeader("Accept", APPLICATION_JSON + ", " + TEXT_EVENT_STREAM);
+		request.addHeader(HttpHeaders.PROTOCOL_VERSION, ProtocolVersions.MCP_2025_03_26);
+
+		mcpStatelessServerTransport.service(request, response);
+
+		assertThat(response.getStatus()).isEqualTo(HttpServletResponse.SC_NOT_FOUND);
+
+		McpSchema.JSONRPCResponse jsonrpcResponse = JSON_MAPPER.readValue(response.getContentAsByteArray(),
+				McpSchema.JSONRPCResponse.class);
+
+		assertThat(jsonrpcResponse).isNotNull();
+		assertThat(jsonrpcResponse.error()).isNotNull();
+		assertThat(jsonrpcResponse.error().code()).isEqualTo(ErrorCodes.METHOD_NOT_FOUND);
+		assertThat(jsonrpcResponse.error().message()).isEqualTo("Method not found: server/discover");
+
+		mcpServer.close();
+	}
+
 	private double evaluateExpression(String expression) {
 		// Simple expression evaluator for testing
 		return switch (expression) {