diff --git a/packages/components/package-lock.json b/packages/components/package-lock.json
index 55d169e8b9..9fc7e03a18 100644
--- a/packages/components/package-lock.json
+++ b/packages/components/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@labkey/components",
-  "version": "7.24.1",
+  "version": "7.24.2-fb-mvtcOptions.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@labkey/components",
-      "version": "7.24.1",
+      "version": "7.24.2-fb-mvtcOptions.1",
       "license": "SEE LICENSE IN LICENSE.txt",
       "dependencies": {
         "@hello-pangea/dnd": "18.0.1",
diff --git a/packages/components/package.json b/packages/components/package.json
index 19e985a1a3..acb8039336 100644
--- a/packages/components/package.json
+++ b/packages/components/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@labkey/components",
-  "version": "7.24.1",
+  "version": "7.24.2-fb-mvtcOptions.1",
   "description": "Components, models, actions, and utility functions for LabKey applications and pages",
   "sideEffects": false,
   "files": [
diff --git a/packages/components/releaseNotes/components.md b/packages/components/releaseNotes/components.md
index a352005755..3e1283f9c8 100644
--- a/packages/components/releaseNotes/components.md
+++ b/packages/components/releaseNotes/components.md
@@ -1,6 +1,10 @@
 # @labkey/components
 Components, models, actions, and utility functions for LabKey applications and pages
 
+### version 7.X
+*Released*: X March 2026
+- GitHub Issue 955: limit text choice option length to 200 characters
+
 ### version 7.24.1
 *Released*: 25 March 2026
 - Factor `EditingForm` out of `EditableDetailPanel` and load model with update columns
diff --git a/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.test.tsx b/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.test.tsx
index 93f43c3382..6d6862d056 100644
--- a/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.test.tsx
+++ b/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.test.tsx
@@ -79,6 +79,33 @@ describe('TextChoiceAddValuesModal', () => {
         validateCounterText('2 values', '3 new values');
     });
 
+    test('value exceeding max length disables apply and shows error', async () => {
+        render(<TextChoiceAddValuesModal {...DEFAULT_PROPS} />);
+        const longValue = 'a'.repeat(201);
+        await userEvent.type(document.querySelector('textarea'), longValue);
+        expect(document.querySelector('.btn-success').hasAttribute('disabled')).toBeTruthy();
+        let errorEls = document.querySelectorAll('.domain-text-choices-error');
+        expect(errorEls).toHaveLength(1);
+        expect(errorEls[0].textContent).toContain('Value exceeds maximum of 200 characters');
+
+        // clear the long value, error should be gone
+        await userEvent.clear(document.querySelector('textarea'));
+        expect(document.querySelectorAll('.domain-text-choices-error')).toHaveLength(0);
+
+        // enter a valid short value, no error
+        await userEvent.type(document.querySelector('textarea'), 'short value');
+        expect(document.querySelector('.btn-success').hasAttribute('disabled')).toBeFalsy();
+        expect(document.querySelectorAll('.domain-text-choices-error')).toHaveLength(0);
+
+        // multiline input where second line exceeds max length
+        await userEvent.clear(document.querySelector('textarea'));
+        await userEvent.type(document.querySelector('textarea'), 'valid\n' + 'b'.repeat(201));
+        expect(document.querySelector('.btn-success').hasAttribute('disabled')).toBeTruthy();
+        errorEls = document.querySelectorAll('.domain-text-choices-error');
+        expect(errorEls).toHaveLength(1);
+        expect(errorEls[0].textContent).toContain('Value exceeds maximum of 200 characters');
+    });
+
     test('initial already equal to max', async () => {
         render(<TextChoiceAddValuesModal {...DEFAULT_PROPS} initialValueCount={2} maxValueCount={2} />);
         expect(document.querySelector('.btn-success').hasAttribute('disabled')).toBeTruthy();
diff --git a/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.tsx b/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.tsx
index 3e6758d806..ad7cdc2914 100644
--- a/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.tsx
+++ b/packages/components/src/internal/components/domainproperties/TextChoiceAddValuesModal.tsx
@@ -4,7 +4,7 @@ import { Utils } from '@labkey/api';
 
 import { Modal } from '../../Modal';
 
-import { MAX_VALID_TEXT_CHOICES } from './constants';
+import { MAX_TEXT_CHOICE_VALUE_LENGTH, MAX_VALID_TEXT_CHOICES } from './constants';
 import { getValidValuesFromArray } from './models';
 
 interface Props {
@@ -22,27 +22,31 @@ export const TextChoiceAddValuesModal: FC<Props> = memo(props => {
         return valueStr?.trim().length > 0 ? getValidValuesFromArray(valueStr.split('\n').map(v => v.trim())) : [];
     }, [valueStr]);
     const maxValuesToAdd = useMemo(() => maxValueCount - initialValueCount, [initialValueCount]);
+    const tooLongValue = useMemo(() => parsedValues.find(v => v.length > MAX_TEXT_CHOICE_VALUE_LENGTH), [parsedValues]);
     const hasFieldName = useMemo(() => fieldName?.length > 0, [fieldName]);
     const onChange = useCallback(evt => {
         setValueStr(evt.target.value);
     }, []);
     const onConfirm = useCallback(() => {
-        if (parsedValues.length <= maxValuesToAdd) {
+        if (parsedValues.length <= maxValuesToAdd && !tooLongValue) {
             onApply(parsedValues);
         }
-    }, [parsedValues, maxValuesToAdd, onApply]);
-    const canConfirm = parsedValues.length > 0 && parsedValues.length <= maxValuesToAdd;
+    }, [parsedValues, maxValuesToAdd, tooLongValue, onApply]);
+    const canConfirm = parsedValues.length > 0 && parsedValues.length <= maxValuesToAdd && !tooLongValue;
     const title = `Add Text Choice Values${hasFieldName ? ' for ' + fieldName : ''}`;
     const valueNoun = Utils.pluralize(maxValuesToAdd, 'value', 'values');
     return (
         <Modal canConfirm={canConfirm} confirmText="Apply" onCancel={onCancel} onConfirm={onConfirm} title={title}>
             <p>Enter each value on a new line. {valueNoun} can be added.</p>
             <textarea
-                rows={8}
-                cols={50}
+                aria-label="Text choice values"
+                aria-describedby={tooLongValue ? 'text-choice-length-error' : undefined}
+                aria-invalid={!!tooLongValue}
                 className="form-control textarea-fullwidth"
-                placeholder="Enter new values..."
+                cols={50}
                 onChange={onChange}
+                placeholder="Enter new values..."
+                rows={8}
                 value={valueStr}
             />
             <div
@@ -52,6 +56,12 @@ export const TextChoiceAddValuesModal: FC<Props> = memo(props => {
             >
                 {parsedValues.length === 1 ? '1 new value provided.' : `${parsedValues.length} new values provided.`}
             </div>
+            {tooLongValue && (
+                <div className="domain-text-choices-error" id="text-choice-length-error" role="alert">
+                    Value exceeds maximum of {MAX_TEXT_CHOICE_VALUE_LENGTH} characters: &quot;
+                    {tooLongValue.substring(0, 50)}...&quot;
+                </div>
+            )}
         </Modal>
     );
 });
diff --git a/packages/components/src/internal/components/domainproperties/constants.ts b/packages/components/src/internal/components/domainproperties/constants.ts
index a3491e2a37..eaa144c869 100644
--- a/packages/components/src/internal/components/domainproperties/constants.ts
+++ b/packages/components/src/internal/components/domainproperties/constants.ts
@@ -233,6 +233,7 @@ export const DERIVATION_DATA_SCOPES = {
 };
 
 export const MAX_VALID_TEXT_CHOICES = 500;
+export const MAX_TEXT_CHOICE_VALUE_LENGTH = 200; // GitHub Issue 955: limit option length to 200
 
 export const LOOKUP_VALIDATOR_VALUES = { type: 'Lookup', name: 'Lookup Validator' };