diff --git a/web/src/popover_menus_data.js b/web/src/popover_menus_data.js
index cd7f158910..3d6286ce49 100644
--- a/web/src/popover_menus_data.js
+++ b/web/src/popover_menus_data.js
@@ -16,6 +16,7 @@ import * as settings_data from "./settings_data";
 import * as starred_messages from "./starred_messages";
 import * as stream_data from "./stream_data";
 import * as sub_store from "./sub_store";
+import {num_unread_for_topic} from "./unread";
 import {user_settings} from "./user_settings";
 import * as user_status from "./user_status";
 import * as user_topics from "./user_topics";
@@ -118,6 +119,7 @@ export function get_topic_popover_content_context({stream_id, topic_name, url})
     const sub = sub_store.get(stream_id);
     const topic_unmuted = user_topics.is_topic_unmuted(sub.stream_id, topic_name);
     const has_starred_messages = starred_messages.get_count_in_topic(sub.stream_id, topic_name) > 0;
+    const has_unread_messages = num_unread_for_topic(sub.stream_id, topic_name) > 0;
     const can_move_topic = settings_data.user_can_move_messages_between_streams();
     const can_rename_topic = settings_data.user_can_move_messages_to_another_topic();
     const visibility_policy = user_topics.get_topic_visibility_policy(sub.stream_id, topic_name);
@@ -133,6 +135,7 @@ export function get_topic_popover_content_context({stream_id, topic_name, url})
         is_realm_admin: page_params.is_admin,
         topic_is_resolved: resolved_topic.is_resolved(topic_name),
         has_starred_messages,
+        has_unread_messages,
         url,
         visibility_policy,
         all_visibility_policies,
diff --git a/web/src/topic_popover.js b/web/src/topic_popover.js
index ddd8e0bd85..7f7d579088 100644
--- a/web/src/topic_popover.js
+++ b/web/src/topic_popover.js
@@ -123,6 +123,11 @@ export function initialize() {
                     instance.hide();
                 });
 
+                $popper.one("click", ".sidebar-popover-mark-topic-unread", () => {
+                    unread_ops.mark_topic_as_unread(stream_id, topic_name);
+                    instance.hide();
+                });
+
                 $popper.one("click", ".sidebar-popover-delete-topic-messages", () => {
                     const html_body = render_delete_topic_modal({topic_name});
 
diff --git a/web/src/unread_ops.js b/web/src/unread_ops.js
index a64852df68..8cfb895a56 100644
--- a/web/src/unread_ops.js
+++ b/web/src/unread_ops.js
@@ -498,6 +498,20 @@ export function mark_topic_as_read(stream_id, topic) {
     );
 }
 
+export function mark_topic_as_unread(stream_id, topic) {
+    bulk_update_read_flags_for_narrow(
+        [
+            {operator: "stream", operand: stream_id},
+            {operator: "topic", operand: topic},
+        ],
+        "remove",
+        {
+            stream_id,
+            topic,
+        },
+    );
+}
+
 export function mark_all_as_read() {
     bulk_update_read_flags_for_narrow(all_unread_messages_narrow, "add");
 }
diff --git a/web/templates/topic_sidebar_actions.hbs b/web/templates/topic_sidebar_actions.hbs
index 07b1274b1e..d45dedc684 100644
--- a/web/templates/topic_sidebar_actions.hbs
+++ b/web/templates/topic_sidebar_actions.hbs
@@ -35,12 +35,21 @@
     </li>
     {{/if}}
 
+    {{#if has_unread_messages}}
     <li class="topic-menu-item hidden-for-spectators">
         <a tabindex="0" class="sidebar-popover-mark-topic-read" data-stream-id="{{ stream_id }}" data-topic-name="{{ topic_name }}">
             <i class="fa fa-book" aria-hidden="true"></i>
             {{t "Mark all messages as read"}}
         </a>
     </li>
+    {{else}}
+    <li class="topic-menu-item hidden-for-spectators">
+        <a tabindex="0" class="sidebar-popover-mark-topic-unread" data-stream-id="{{ stream_id }}" data-topic-name="{{ topic_name }}">
+            <i class="fa fa-book" aria-hidden="true"></i>
+            {{t "Mark all messages as unread"}}
+        </a>
+    </li>
+    {{/if}}
 
     <li class="topic-menu-item">
         <a tabindex="0" class="sidebar-popover-copy-link-to-topic" data-stream-id="{{ stream_id }}" data-topic-name="{{ topic_name }}" data-clipboard-text="{{ url }}">