diff --git a/app/actions/local/channel.ts b/app/actions/local/channel.ts
index 090441b51..729fddb29 100644
--- a/app/actions/local/channel.ts
+++ b/app/actions/local/channel.ts
@@ -189,7 +189,7 @@ export const markChannelAsViewed = async (serverUrl: string, channelId: string,
     }
 };
 
-export const markChannelAsUnread = async (serverUrl: string, channelId: string, messageCount: number, mentionsCount: number, manuallyUnread: boolean, lastViewed: number, prepareRecordsOnly = false) => {
+export const markChannelAsUnread = async (serverUrl: string, channelId: string, messageCount: number, mentionsCount: number, lastViewed: number, prepareRecordsOnly = false) => {
     const operator = DatabaseManager.serverDatabases[serverUrl]?.operator;
     if (!operator) {
         return {error: `${serverUrl} database not found`};
@@ -201,11 +201,12 @@ export const markChannelAsUnread = async (serverUrl: string, channelId: string,
     }
 
     member.prepareUpdate((m) => {
-        m.viewedAt = lastViewed;
+        m.viewedAt = lastViewed - 1;
         m.lastViewedAt = lastViewed;
         m.messageCount = messageCount;
         m.mentionsCount = mentionsCount;
-        m.manuallyUnread = manuallyUnread;
+        m.manuallyUnread = true;
+        m.isUnread = true;
     });
 
     try {
diff --git a/app/actions/remote/post.ts b/app/actions/remote/post.ts
index 26f3e299d..dd7f7cfd1 100644
--- a/app/actions/remote/post.ts
+++ b/app/actions/remote/post.ts
@@ -4,7 +4,7 @@
 
 import {DeviceEventEmitter} from 'react-native';
 
-import {updateLastPostAt} from '@actions/local/channel';
+import {markChannelAsUnread, updateLastPostAt} from '@actions/local/channel';
 import {processPostsFetched, removePost} from '@actions/local/post';
 import {addRecentReaction} from '@actions/local/reactions';
 import {ActionType, Events, General, ServerErrors} from '@constants';
@@ -575,3 +575,43 @@ export const deletePost = async (serverUrl: string, postId: string) => {
         return {error};
     }
 };
+
+export const markPostAsUnread = async (serverUrl: string, postId: string) => {
+    const database = DatabaseManager.serverDatabases[serverUrl]?.database;
+    if (!database) {
+        return {error: `${serverUrl} database not found`};
+    }
+    let client;
+    try {
+        client = NetworkManager.getClient(serverUrl);
+    } catch (error) {
+        return {error};
+    }
+
+    try {
+        const [userId, post] = await Promise.all([queryCurrentUserId(database), queryPostById(database, postId)]);
+        if (post && userId) {
+            await client.markPostAsUnread(userId, postId);
+            const {channelId} = post;
+
+            const [channel, channelMember] = await Promise.all([
+                client.getChannel(channelId),
+                client.getChannelMember(channelId, userId),
+            ]);
+            if (channel && channelMember) {
+                const messageCount = channel.total_msg_count - channelMember.msg_count;
+                const mentionCount = channelMember.mention_count;
+                await markChannelAsUnread(serverUrl, channelId, messageCount, mentionCount, post.createAt);
+                return {
+                    post,
+                };
+            }
+        }
+        return {
+            post,
+        };
+    } catch (error) {
+        forceLogoutIfNecessary(serverUrl, error as ClientErrorProps);
+        return {error};
+    }
+};
diff --git a/app/actions/websocket/posts.ts b/app/actions/websocket/posts.ts
index 84cc9a34a..17b71d1ff 100644
--- a/app/actions/websocket/posts.ts
+++ b/app/actions/websocket/posts.ts
@@ -152,9 +152,7 @@ export async function handleNewPostEvent(serverUrl: string, msg: WebSocketMessag
                 post.channel_id,
                 myChannel.messageCount + 1,
                 myChannel.mentionsCount + (hasMentions ? 1 : 0),
-                false,
                 myChannel.lastViewedAt,
-                true,
             );
             if (unreadAt) {
                 models.push(unreadAt);
@@ -217,5 +215,5 @@ export async function handlePostUnread(serverUrl: string, msg: WebSocketMessage)
     const channel = channels?.[0];
     const postNumber = channel?.total_msg_count;
     const delta = postNumber ? postNumber - msg.data.msg_count : msg.data.msg_count;
-    markChannelAsUnread(serverUrl, msg.broadcast.channel_id, delta, msg.data.mention_count, true, msg.data.last_viewed_at);
+    markChannelAsUnread(serverUrl, msg.broadcast.channel_id, delta, msg.data.mention_count, msg.data.last_viewed_at);
 }
diff --git a/app/screens/post_options/options/mark_unread_option.tsx b/app/screens/post_options/options/mark_unread_option.tsx
index 745f4da57..14805ead1 100644
--- a/app/screens/post_options/options/mark_unread_option.tsx
+++ b/app/screens/post_options/options/mark_unread_option.tsx
@@ -1,24 +1,34 @@
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.
 
-import React from 'react';
+import React, {useCallback} from 'react';
 
+import {markPostAsUnread} from '@actions/remote/post';
+import Screens from '@constants/screens';
+import {useServerUrl} from '@context/server';
 import {t} from '@i18n';
+import {dismissBottomSheet} from '@screens/navigation';
 
 import BaseOption from './base_option';
 
-//fixme: wire up canMarkAsUnread
-const MarkAsUnreadOption = () => {
-    const handleMarkUnread = () => {
-        //todo:
-    };
+type Props = {
+    postId: string;
+}
+
+const MarkAsUnreadOption = ({postId}: Props) => {
+    const serverUrl = useServerUrl();
+
+    const onPress = useCallback(() => {
+        markPostAsUnread(serverUrl, postId);
+        dismissBottomSheet(Screens.POST_OPTIONS);
+    }, [serverUrl, postId]);
 
     return (
         <BaseOption
             i18nId={t('mobile.post_info.mark_unread')}
             defaultMessage='Mark as Unread'
             iconName='mark-as-unread'
-            onPress={handleMarkUnread}
+            onPress={onPress}
             testID='post.options.mark.unread'
         />
     );
diff --git a/app/screens/post_options/post_options.tsx b/app/screens/post_options/post_options.tsx
index e0076e115..eeecc936b 100644
--- a/app/screens/post_options/post_options.tsx
+++ b/app/screens/post_options/post_options.tsx
@@ -74,7 +74,9 @@ const PostOptions = ({
                         thread={thread}
                     />
                 }
-                {canMarkAsUnread && !isSystemPost && (<MarkAsUnreadOption/>)}
+                {canMarkAsUnread && !isSystemPost &&
+                    <MarkAsUnreadOption postId={post.id}/>
+                }
                 {canCopyPermalink && <CopyLinkOption post={post}/>}
                 {!isSystemPost &&
                     <SaveOption