diff --git a/actions/websocket_actions.jsx b/actions/websocket_actions.jsx
index 1bed58a68202..14aa7e41e049 100644
--- a/actions/websocket_actions.jsx
+++ b/actions/websocket_actions.jsx
@@ -41,6 +41,7 @@ import {
     handleThreadArrived,
     handleAllThreadsInChannelMarkedRead,
     updateThreadRead,
+    decrementThreadCounts,
 } from 'mattermost-redux/actions/threads';
 
 import {setServerVersion} from 'mattermost-redux/actions/general';
@@ -684,11 +685,17 @@ export function handlePostEditEvent(msg) {
 
 async function handlePostDeleteEvent(msg) {
     const post = JSON.parse(msg.data.post);
+    const state = getState();
+    const collapsedThreads = isCollapsedThreadsEnabled(state);
+
+    if (!post.root_id && collapsedThreads) {
+        dispatch(decrementThreadCounts(post));
+    }
+
     dispatch(postDeleted(post));
 
     // update thread when a comment is deleted and CRT is on
-    const state = getState();
-    if (post.root_id && isCollapsedThreadsEnabled(state)) {
+    if (post.root_id && collapsedThreads) {
         const thread = getThread(state, post.root_id);
         if (thread) {
             const userId = getCurrentUserId(state);
diff --git a/packages/mattermost-redux/src/action_types/threads.ts b/packages/mattermost-redux/src/action_types/threads.ts
index 123bfe9f7a64..54f58f6ccc11 100644
--- a/packages/mattermost-redux/src/action_types/threads.ts
+++ b/packages/mattermost-redux/src/action_types/threads.ts
@@ -9,4 +9,5 @@ export default keyMirror({
     FOLLOW_CHANGED_THREAD: null,
     READ_CHANGED_THREAD: null,
     ALL_TEAM_THREADS_READ: null,
+    DECREMENT_THREAD_COUNTS: null,
 });
diff --git a/packages/mattermost-redux/src/actions/posts.ts b/packages/mattermost-redux/src/actions/posts.ts
index e431d58d76f3..944d4b803afe 100644
--- a/packages/mattermost-redux/src/actions/posts.ts
+++ b/packages/mattermost-redux/src/actions/posts.ts
@@ -29,6 +29,7 @@ import {bindClientFunc, forceLogoutIfNecessary} from './helpers';
 import {logError} from './errors';
 import {systemEmojis, getCustomEmojiByName, getCustomEmojisByName} from './emojis';
 import {selectChannel} from './channels';
+import {decrementThreadCounts} from './threads';
 
 // receivedPost should be dispatched after a single post from the server. This typically happens when an existing post
 // is updated.
@@ -382,6 +383,9 @@ export function deletePost(post: ExtendedPost) {
     return async (dispatch: DispatchFunc, getState: GetStateFunc) => {
         const state = getState();
         const delPost = {...post};
+        if (!post.root_id && isCollapsedThreadsEnabled(state)) {
+            dispatch(decrementThreadCounts(post));
+        }
         if (delPost.type === Posts.POST_TYPES.COMBINED_USER_ACTIVITY && delPost.system_post_ids) {
             delPost.system_post_ids.forEach((systemPostId) => {
                 const systemPost = Selectors.getPost(state, systemPostId);
diff --git a/packages/mattermost-redux/src/actions/threads.ts b/packages/mattermost-redux/src/actions/threads.ts
index 8f29e97d8530..a67d4acde1fb 100644
--- a/packages/mattermost-redux/src/actions/threads.ts
+++ b/packages/mattermost-redux/src/actions/threads.ts
@@ -12,13 +12,15 @@ import {DispatchFunc, GetStateFunc, batchActions} from 'mattermost-redux/types/a
 
 import type {UserThread, UserThreadList} from 'mattermost-redux/types/threads';
 
+import {Post} from 'mattermost-redux/types/posts';
+
 import {getMissingProfilesByIds} from 'mattermost-redux/actions/users';
 
 import {getCurrentUserId} from 'mattermost-redux/selectors/entities/users';
 
 import {getCurrentTeamId} from 'mattermost-redux/selectors/entities/teams';
 
-import {getThreadsInChannel} from 'mattermost-redux/selectors/entities/threads';
+import {getThreadsInChannel, getThread as getThreadSelector} from 'mattermost-redux/selectors/entities/threads';
 
 import {getChannel} from 'mattermost-redux/selectors/entities/channels';
 
@@ -27,6 +29,8 @@ import {isCollapsedThreadsEnabled} from 'mattermost-redux/selectors/entities/pre
 import {logError} from './errors';
 import {forceLogoutIfNecessary} from './helpers';
 
+type ExtendedPost = Post & { system_post_ids?: string[] };
+
 export function getThreads(userId: string, teamId: string, {before = '', after = '', perPage = ThreadConstants.THREADS_CHUNK_SIZE, unread = false, totalsOnly = false} = {}) {
     return async (dispatch: DispatchFunc, getState: GetStateFunc) => {
         let userThreadList: undefined | UserThreadList;
@@ -249,3 +253,25 @@ export function handleAllThreadsInChannelMarkedRead(dispatch: DispatchFunc, getS
 
     dispatch(batchActions(actions));
 }
+
+export function decrementThreadCounts(post: ExtendedPost) {
+    return (dispatch: DispatchFunc, getState: GetStateFunc) => {
+        const state = getState();
+        const thread = getThreadSelector(state, post.id);
+
+        if (!thread || (thread.unread_replies === 0 && thread.unread_mentions === 0)) {
+            return {data: false};
+        }
+
+        const channel = getChannel(state, post.channel_id);
+        const teamId = channel?.team_id || getCurrentTeamId(state);
+
+        return dispatch({
+            type: ThreadTypes.DECREMENT_THREAD_COUNTS,
+            teamId,
+            replies: thread.unread_replies,
+            mentions: thread.unread_mentions,
+            channelType: channel.type,
+        });
+    };
+}
diff --git a/packages/mattermost-redux/src/reducers/entities/threads/counts.ts b/packages/mattermost-redux/src/reducers/entities/threads/counts.ts
index ee5e9693c33f..7d17b7a8686a 100644
--- a/packages/mattermost-redux/src/reducers/entities/threads/counts.ts
+++ b/packages/mattermost-redux/src/reducers/entities/threads/counts.ts
@@ -6,6 +6,8 @@ import {GenericAction} from 'mattermost-redux/types/actions';
 import {ThreadsState, UserThread} from 'mattermost-redux/types/threads';
 import {Team, TeamUnread} from 'mattermost-redux/types/teams';
 
+import Constants from 'utils/constants';
+
 import {ExtraData} from './types';
 
 function handleAllTeamThreadsRead(state: ThreadsState['counts'], action: GenericAction): ThreadsState['counts'] {
@@ -93,6 +95,23 @@ function handleLeaveChannel(state: ThreadsState['counts'] = {}, action: GenericA
     };
 }
 
+function handleDecrementThreadCounts(state: ThreadsState['counts'], action: GenericAction) {
+    const {teamId, replies, mentions} = action;
+    const counts = state[teamId];
+    if (!counts) {
+        return state;
+    }
+
+    return {
+        ...state,
+        [teamId]: {
+            total: Math.max(counts.total - 1, 0),
+            total_unread_mentions: Math.max(counts.total_unread_mentions - mentions, 0),
+            total_unread_threads: Math.max(counts.total_unread_threads - replies, 0),
+        },
+    };
+}
+
 export function countsIncludingDirectReducer(state: ThreadsState['counts'] = {}, action: GenericAction, extra: ExtraData) {
     switch (action.type) {
     case ThreadTypes.ALL_TEAM_THREADS_READ:
@@ -129,6 +148,8 @@ export function countsIncludingDirectReducer(state: ThreadsState['counts'] = {},
                 total_unread_mentions: action.data.total_unread_mentions,
             },
         };
+    case ThreadTypes.DECREMENT_THREAD_COUNTS:
+        return handleDecrementThreadCounts(state, action);
     case UserTypes.LOGOUT_SUCCESS:
         return {};
     }
@@ -163,6 +184,13 @@ export function countsReducer(state: ThreadsState['counts'] = {}, action: Generi
             }, {}),
         };
     }
+    case ThreadTypes.DECREMENT_THREAD_COUNTS: {
+        const {channelType} = action;
+        if (channelType === Constants.DM_CHANNEL || channelType === Constants.GM_CHANNEL) {
+            return state;
+        }
+        return handleDecrementThreadCounts(state, action);
+    }
     }
     return state;
 }