diff --git a/src/apps/opportunities/README.md b/src/apps/opportunities/README.md
index 10d4e2dc9..dbc402196 100644
--- a/src/apps/opportunities/README.md
+++ b/src/apps/opportunities/README.md
@@ -886,3 +886,15 @@ The shared toolbar includes configured Filestack attachments through
 Figma grouping (dividers between formatting, heading, size, alignment, list,
 insert and expand controls, plus the size chevron) lives in the shared editor
 styles, so challenge discussion composers match the public forums.
+
+### Challenge forum notifications
+
+The Challenge Forum overview includes a Watch forum / Unwatch forum control,
+including for empty forums. It reads the authenticated member's effective
+preference from `GET /v6/forums/challenges/:challengeId/watch` and saves choices
+with PUT or DELETE on that route. The Forums API defaults registrants and
+copilots to watching based on their challenge resource assignments and persists
+explicit opt-outs. Topic-specific watches remain independent. Loading and failed
+reads disable the control; failed saves preserve the displayed preference and
+show the API error. This requires the Forums API challenge-watch migration and
+endpoints to be deployed first.
diff --git a/src/apps/opportunities/src/components/ChallengeForum.spec.tsx b/src/apps/opportunities/src/components/ChallengeForum.spec.tsx
index 7ff8aee76..59667495e 100644
--- a/src/apps/opportunities/src/components/ChallengeForum.spec.tsx
+++ b/src/apps/opportunities/src/components/ChallengeForum.spec.tsx
@@ -38,6 +38,10 @@ const mockGetForumTopicDetail = jest.fn()
 const mockMarkForumTopicRead = jest.fn()
 const mockSetForumPostReaction = jest.fn()
 const mockSetForumTopicWatching = jest.fn()
+const mockSetChallengeForumWatching = jest.fn()
+const mockMutateForumWatch = jest.fn()
+let forumWatching: boolean | undefined
+let watchError: Error | undefined
 const mockUseSWR = jest.fn()
 const mockUpdateForumPost = jest.fn()
 const mockUpdateForumTopic = jest.fn()
@@ -101,9 +105,11 @@ jest.mock('../services', () => ({
     deleteForumPost: (...args: unknown[]) => mockDeleteForumPost(...args),
     deleteForumTopic: (...args: unknown[]) => mockDeleteForumTopic(...args),
     getChallengeForumTopics: jest.fn(),
+    getChallengeForumWatch: jest.fn(),
     getForumTopicDetail: (...args: unknown[]) => mockGetForumTopicDetail(...args),
     getMemberProfilesByUserIds: jest.fn(),
     markForumTopicRead: (...args: unknown[]) => mockMarkForumTopicRead(...args),
+    setChallengeForumWatching: (...args: unknown[]) => mockSetChallengeForumWatching(...args),
     setForumPostReaction: (...args: unknown[]) => mockSetForumPostReaction(...args),
     setForumTopicWatching: (...args: unknown[]) => mockSetForumTopicWatching(...args),
     updateForumPost: (...args: unknown[]) => mockUpdateForumPost(...args),
@@ -231,7 +237,22 @@ describe('ChallengeForum', () => {
         }
         topicDetail = { posts: [starterPost], topic: announcement }
         mockGetForumTopicDetail.mockResolvedValue(topicDetail)
+        forumWatching = true
+        watchError = undefined
+        mockSetChallengeForumWatching.mockReset()
+        mockMutateForumWatch.mockReset()
         mockUseSWR.mockImplementation((key: unknown) => {
+            if (Array.isArray(key) && key[0] === 'opportunities:forum-watch') {
+                return {
+                    data: forumWatching === undefined ? undefined : {
+                        challengeId: 'challenge-id', memberId: '10', watching: forumWatching,
+                    },
+                    error: watchError,
+                    isValidating: false,
+                    mutate: mockMutateForumWatch,
+                }
+            }
+
             if (Array.isArray(key) && key[0] === 'opportunities:forum-topics') {
                 return {
                     data: topicCollection,
@@ -315,6 +336,52 @@ describe('ChallengeForum', () => {
             .not.toBeInTheDocument()
     })
 
+    it('unwatches an empty forum and displays the saved preference', async () => {
+        topicCollection = { data: [], sourceTotalCount: 0, truncated: false }
+        const saved = { challengeId: 'challenge-id', memberId: '10', watching: false }
+        mockSetChallengeForumWatching.mockResolvedValue(saved)
+        const view = render(<ChallengeForum challenge={{ id: 'challenge-id', name: 'Challenge' }} memberId='10' />)
+        const button = screen.getByRole('button', { name: 'Unwatch forum' })
+        expect(button)
+            .toHaveAttribute('aria-pressed', 'true')
+        fireEvent.click(button)
+        await waitFor(() => expect(mockMutateForumWatch)
+            .toHaveBeenCalledWith(saved, false))
+        expect(mockSetChallengeForumWatching)
+            .toHaveBeenCalledWith('challenge-id', false)
+        forumWatching = false
+        view.rerender(<ChallengeForum challenge={{ id: 'challenge-id', name: 'Challenge' }} memberId='10' />)
+        expect(screen.getByRole('button', { name: 'Watch forum' }))
+            .toHaveAttribute('aria-pressed', 'false')
+        fireEvent.click(screen.getByRole('button', { name: 'Watch forum' }))
+        await waitFor(() => expect(mockSetChallengeForumWatching)
+            .toHaveBeenCalledWith('challenge-id', true))
+    })
+
+    it('preserves the watch preference when saving fails', async () => {
+        mockSetChallengeForumWatching.mockRejectedValue(new Error('Unable to save preference'))
+        render(<ChallengeForum challenge={{ id: 'challenge-id', name: 'Challenge' }} memberId='10' />)
+        fireEvent.click(screen.getByRole('button', { name: 'Unwatch forum' }))
+        await screen.findByText('Unable to save preference')
+        expect(mockMutateForumWatch).not.toHaveBeenCalled()
+        expect(screen.getByRole('button', { name: 'Unwatch forum' }))
+            .toBeEnabled()
+    })
+
+    it('disables the watch control while its preference is loading or unavailable', () => {
+        forumWatching = undefined
+        const view = render(<ChallengeForum challenge={{ id: 'challenge-id', name: 'Challenge' }} memberId='10' />)
+        expect(screen.getByRole('button', { name: 'Watch forum' }))
+            .toBeDisabled()
+        watchError = new Error('Unavailable')
+        view.rerender(<ChallengeForum challenge={{ id: 'challenge-id', name: 'Challenge' }} memberId='10' />)
+        expect(screen.getByRole('button', { name: 'Watch forum' }))
+            .toBeDisabled()
+        fireEvent.click(screen.getByRole('button', { name: 'Retry' }))
+        expect(mockMutateForumWatch)
+            .toHaveBeenCalled()
+    })
+
     it('uses the API source total for topic counters', () => {
         topicCollection = {
             data: [announcement, discussion],
diff --git a/src/apps/opportunities/src/components/ChallengeForum.tsx b/src/apps/opportunities/src/components/ChallengeForum.tsx
index 9e1e9b687..cd455ffbd 100644
--- a/src/apps/opportunities/src/components/ChallengeForum.tsx
+++ b/src/apps/opportunities/src/components/ChallengeForum.tsx
@@ -7,6 +7,7 @@ import { uploadForumAttachment } from '../services/forum-attachments.service'
 import { ForumIcon } from './ForumIcon'
 
 import {
+    ChallengeForumWatchState,
     ChallengeOpportunity,
     ForumPost,
     ForumPostReaction,
@@ -21,9 +22,11 @@ import {
     deleteForumPost,
     deleteForumTopic,
     getChallengeForumTopics,
+    getChallengeForumWatch,
     getForumTopicDetail,
     getMemberProfilesByUserIds,
     markForumTopicRead,
+    setChallengeForumWatching,
     setForumPostReaction,
     setForumTopicWatching,
     updateForumPost,
@@ -368,7 +371,7 @@ const ForumFallback: FC<ForumFallbackProps> = props => (
 /**
  * Renders challenge forum counters and the available in-page creation actions.
  *
- * @param props visible topics, source total, ordinary creation, and administrator announcement creation.
+ * @param props visible topics, counts, creation actions, and challenge-wide watch state/control.
  * @returns authored forum overview rail.
  * @throws Does not throw.
  */
@@ -376,6 +379,9 @@ const ForumOverview: FC<{
     canCreateAnnouncements: boolean
     onCreate: () => void
     onCreateAnnouncement: () => void
+    onWatch: () => void
+    watchDisabled: boolean
+    watching?: boolean
     topics: ForumTopicSummary[]
     total: number
 }> = props => {
@@ -404,6 +410,15 @@ const ForumOverview: FC<{
                 </span>
             </div>
             <div className={styles.overviewActions}>
+                <button
+                    aria-pressed={props.watching ?? false}
+                    disabled={props.watchDisabled}
+                    onClick={props.onWatch}
+                    type='button'
+                >
+                    <IconOutline.EyeIcon aria-hidden='true' />
+                    {props.watching ? 'Unwatch forum' : 'Watch forum'}
+                </button>
                 <button onClick={props.onCreate} type='button'>
                     <IconOutline.PlusCircleIcon aria-hidden='true' />
                     Create new topic
@@ -1724,8 +1739,8 @@ function resetForumScroll(): void {
  *
  * The component keeps every communication workflow inside Opportunities:
  * topic create/edit/delete, nested replies, post edit/delete, reaction toggles,
- * watch state, and read state. A legacy link is retained only as recovery when
- * the v6 API cannot be reached or the member is signed out.
+ * topic and challenge-wide watch preferences, and read state. A legacy link is
+ * retained only as recovery when the v6 API cannot be reached or the member is signed out.
  *
  * @param props challenge context, optional member ID, and administrator announcement/delete access.
  * @returns embedded topic list, creation form, detail discussion, or recovery state.
@@ -1750,6 +1765,11 @@ export const ChallengeForum: FC<ChallengeForumProps> = props => {
         () => getChallengeForumTopics(props.challenge.id),
         { revalidateOnFocus: false },
     )
+    const watchResponse: SWRResponse<ChallengeForumWatchState, Error> = useSWR(
+        props.memberId ? ['opportunities:forum-watch', props.challenge.id, props.memberId] : undefined,
+        () => getChallengeForumWatch(props.challenge.id),
+        { revalidateOnFocus: false },
+    )
     const detailResponse: SWRResponse<ForumTopicDetail, Error> = useSWR(
         selectedTopicId ? ['opportunities:forum-topic', selectedTopicId] : undefined,
         () => getForumTopicDetail(selectedTopicId as string),
@@ -1955,6 +1975,25 @@ export const ChallengeForum: FC<ChallengeForumProps> = props => {
         }
     }
 
+    /**
+     * Persists the overview's forum-wide preference and refreshes its displayed state.
+     * @returns Nothing after the save and cache update finish.
+     * @throws Does not throw; failures preserve the previous state and show an error.
+     */
+    const toggleForumWatch = async (): Promise<void> => {
+        if (!watchResponse.data || pendingAction === 'forum-watch') return
+        setPendingAction('forum-watch')
+        setMutationError(undefined)
+        try {
+            const saved = await setChallengeForumWatching(props.challenge.id, !watchResponse.data.watching)
+            await watchResponse.mutate(saved, false)
+        } catch (error) {
+            setMutationError(forumErrorMessage(error))
+        } finally {
+            setPendingAction(undefined)
+        }
+    }
+
     if (!props.memberId) {
         return (
             <ForumFallback
@@ -2039,6 +2078,9 @@ export const ChallengeForum: FC<ChallengeForumProps> = props => {
         <div className={styles.forumLayout}>
             <aside className={styles.leftPanel}>
                 <ForumOverview
+                    onWatch={toggleForumWatch}
+                    watchDisabled={!watchResponse.data || !!watchResponse.error || pendingAction === 'forum-watch'}
+                    watching={watchResponse.data?.watching}
                     canCreateAnnouncements={!!props.canCreateAnnouncements}
                     onCreate={() => {
                         setMutationError(undefined)
@@ -2075,6 +2117,13 @@ export const ChallengeForum: FC<ChallengeForumProps> = props => {
                 <DiscussionInfo profilesByMemberId={profilesByMemberId} topics={topics} />
             </aside>
             <section aria-label='Forum topics' className={styles.topicList}>
+                {watchResponse.error && (
+                    <p className={styles.actionError} role='alert'>
+                        Forum notification preferences could not be loaded.
+                        {' '}
+                        <button onClick={() => watchResponse.mutate()} type='button'>Retry</button>
+                    </p>
+                )}
                 {mutationError && (
                     <p className={styles.actionError} role='alert'>
                         {mutationError}
diff --git a/src/apps/opportunities/src/models/forum.models.ts b/src/apps/opportunities/src/models/forum.models.ts
index 99af8743a..960f9fbc5 100644
--- a/src/apps/opportunities/src/models/forum.models.ts
+++ b/src/apps/opportunities/src/models/forum.models.ts
@@ -138,3 +138,10 @@ export interface ForumWatchMutationResponse {
     topicId: string
     watching?: boolean
 }
+
+/** Effective current-member watch state for an entire challenge forum. */
+export interface ChallengeForumWatchState {
+    challengeId: string
+    memberId: string
+    watching: boolean
+}
diff --git a/src/apps/opportunities/src/services/forum.service.spec.ts b/src/apps/opportunities/src/services/forum.service.spec.ts
index 6aceb0fac..5f6a94700 100644
--- a/src/apps/opportunities/src/services/forum.service.spec.ts
+++ b/src/apps/opportunities/src/services/forum.service.spec.ts
@@ -5,8 +5,10 @@ import {
     deleteForumPost,
     deleteForumTopic,
     getChallengeForumTopics,
+    getChallengeForumWatch,
     getForumTopicDetail,
     markForumTopicRead,
+    setChallengeForumWatching,
     setForumPostReaction,
     setForumTopicWatching,
     updateForumPost,
@@ -34,6 +36,19 @@ jest.mock('~/libs/core', () => ({
 describe('forum service', () => {
     beforeEach(() => jest.clearAllMocks())
 
+    it('reads and persists challenge-wide watch choices without impersonation fields', async () => {
+        await getChallengeForumWatch('challenge/id')
+        await setChallengeForumWatching('challenge/id', true)
+        await setChallengeForumWatching('challenge/id', false)
+        const url = 'https://api.example/v6/forums/challenges/challenge%2Fid/watch'
+        expect(mockXhrGetAsync)
+            .toHaveBeenCalledWith(url)
+        expect(mockXhrPutAsync)
+            .toHaveBeenCalledWith(url, {})
+        expect(mockXhrDeleteAsync)
+            .toHaveBeenCalledWith(url)
+    })
+
     it('builds an encoded, bounded challenge topic page URL', () => {
         expect(challengeForumTopicsUrl('challenge/id', 0, 0))
             .toBe('https://api.example/v6/forums/topics/challenges/challenge%2Fid?page=1&perPage=1')
diff --git a/src/apps/opportunities/src/services/forum.service.ts b/src/apps/opportunities/src/services/forum.service.ts
index b4a015f77..443d91fdb 100644
--- a/src/apps/opportunities/src/services/forum.service.ts
+++ b/src/apps/opportunities/src/services/forum.service.ts
@@ -8,6 +8,7 @@ import {
 } from '~/libs/core'
 
 import {
+    ChallengeForumWatchState,
     CreateForumPostRequest,
     CreateForumTopicRequest,
     CreateForumTopicResponse,
@@ -275,3 +276,32 @@ export async function markForumTopicRead(topicId: string): Promise<void> {
         {},
     )
 }
+
+/**
+ * Loads the current member's effective challenge-wide watch preference.
+ * @param challengeId challenge whose forum preference is requested.
+ * @returns persisted preference or default derived from registration/copilot assignment.
+ * @throws Propagates authentication, authorization, and network errors.
+ */
+export function getChallengeForumWatch(challengeId: string): Promise<ChallengeForumWatchState> {
+    return xhrGetAsync<ChallengeForumWatchState>(
+        `${FORUMS_URL}/challenges/${encodeURIComponent(challengeId)}/watch`,
+    )
+}
+
+/**
+ * Persists the current member's watch preference for existing and future forum topics.
+ * @param challengeId challenge whose forum preference is updated.
+ * @param watching true to watch, false to persist an opt-out from default notifications.
+ * @returns saved challenge-wide watch state.
+ * @throws Propagates authentication, authorization, and network errors.
+ */
+export function setChallengeForumWatching(
+    challengeId: string,
+    watching: boolean,
+): Promise<ChallengeForumWatchState> {
+    const url = `${FORUMS_URL}/challenges/${encodeURIComponent(challengeId)}/watch`
+    return watching
+        ? xhrPutAsync<Record<string, never>, ChallengeForumWatchState>(url, {})
+        : xhrDeleteAsync<ChallengeForumWatchState>(url)
+}