diff --git a/app/assets/javascripts/discourse/app/components/sidebar/messages-section.js b/app/assets/javascripts/discourse/app/components/sidebar/messages-section.js
index ac57cf32180..7c2ff92c3ab 100644
--- a/app/assets/javascripts/discourse/app/components/sidebar/messages-section.js
+++ b/app/assets/javascripts/discourse/app/components/sidebar/messages-section.js
@@ -2,13 +2,14 @@ import { cached } from "@glimmer/tracking";
 
 import { getOwner } from "discourse-common/lib/get-owner";
 import GlimmerComponent from "discourse/components/glimmer";
+import { bind } from "discourse-common/utils/decorators";
 import GroupMessageSectionLink from "discourse/lib/sidebar/messages-section/group-message-section-link";
 import PersonalMessageSectionLink from "discourse/lib/sidebar/messages-section/personal-message-section-link";
 
 export const INBOX = "inbox";
-const UNREAD = "unread";
+export const UNREAD = "unread";
 const SENT = "sent";
-const NEW = "new";
+export const NEW = "new";
 const ARCHIVE = "archive";
 
 export const PERSONAL_MESSAGES_INBOX_FILTERS = [
@@ -30,6 +31,24 @@ export default class SidebarMessagesSection extends GlimmerComponent {
       this,
       this._refreshSectionLinksDisplayState
     );
+
+    this.pmTopicTrackingState
+      .startTracking()
+      .then(this._refreshSectionLinkCounts);
+
+    this._pmTopicTrackingStateKey = "messages-section";
+
+    this.pmTopicTrackingState.onStateChange(
+      this._pmTopicTrackingStateKey,
+      this._refreshSectionLinkCounts
+    );
+  }
+
+  @bind
+  _refreshSectionLinkCounts() {
+    for (const sectionLink of this.allSectionLinks) {
+      sectionLink.refreshCount();
+    }
   }
 
   willDestroy() {
@@ -38,6 +57,11 @@ export default class SidebarMessagesSection extends GlimmerComponent {
       this,
       this._refreshSectionLinksDisplayState
     );
+
+    this.pmTopicTrackingState.offStateChange(
+      this._pmTopicTrackingStateKey,
+      this._refreshSectionLinkCounts
+    );
   }
 
   _refreshSectionLinksDisplayState({
@@ -81,6 +105,7 @@ export default class SidebarMessagesSection extends GlimmerComponent {
         new PersonalMessageSectionLink({
           currentUser: this.currentUser,
           type,
+          pmTopicTrackingState: this.pmTopicTrackingState,
         })
       );
     });
@@ -99,6 +124,7 @@ export default class SidebarMessagesSection extends GlimmerComponent {
             group,
             type: groupMessageLink,
             currentUser: this.currentUser,
+            pmTopicTrackingState: this.pmTopicTrackingState,
           })
         );
       });
diff --git a/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/group-message-section-link.js b/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/group-message-section-link.js
index 83192a87654..ce6ec8bc7de 100644
--- a/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/group-message-section-link.js
+++ b/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/group-message-section-link.js
@@ -40,6 +40,10 @@ export default class GroupMessageSectionLink extends MessageSectionLink {
   get text() {
     if (this._isInbox) {
       return this.group.name;
+    } else if (this.count > 0) {
+      return I18n.t(`sidebar.sections.messages.links.${this.type}_with_count`, {
+        count: this.count,
+      });
     } else {
       return I18n.t(`sidebar.sections.messages.links.${this.type}`);
     }
diff --git a/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/message-section-link.js b/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/message-section-link.js
index fcd029e2187..bef0aef0951 100644
--- a/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/message-section-link.js
+++ b/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/message-section-link.js
@@ -1,18 +1,42 @@
 import { tracked } from "@glimmer/tracking";
 
-import { INBOX } from "discourse/components/sidebar/messages-section";
+import {
+  INBOX,
+  NEW,
+  UNREAD,
+} from "discourse/components/sidebar/messages-section";
 
 export default class MessageSectionLink {
   @tracked shouldDisplay = this._isInbox;
+  @tracked count = 0;
 
-  constructor({ group, currentUser, type }) {
+  constructor({ group, currentUser, type, pmTopicTrackingState }) {
     this.group = group;
     this.currentUser = currentUser;
     this.type = type;
+    this.pmTopicTrackingState = pmTopicTrackingState;
+  }
+
+  refreshCount() {
+    this._refreshCount();
+  }
+
+  _refreshCount() {
+    if (this.shouldDisplay && this._shouldTrack) {
+      this.count = this.pmTopicTrackingState.lookupCount(this.type, {
+        inboxFilter: this.group ? "group" : "user",
+        groupName: this.group?.name,
+      });
+    }
   }
 
   set setDisplayState(value) {
+    const changed = this.shouldDisplay !== value;
     this.shouldDisplay = value;
+
+    if (changed) {
+      this._refreshCount();
+    }
   }
 
   get inboxFilter() {
@@ -43,4 +67,8 @@ export default class MessageSectionLink {
   get _isInbox() {
     return this.type === INBOX;
   }
+
+  get _shouldTrack() {
+    return this.type === NEW || this.type === UNREAD;
+  }
 }
diff --git a/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/personal-message-section-link.js b/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/personal-message-section-link.js
index dc2c42646fb..bbf813f352e 100644
--- a/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/personal-message-section-link.js
+++ b/app/assets/javascripts/discourse/app/lib/sidebar/messages-section/personal-message-section-link.js
@@ -38,7 +38,13 @@ export default class PersonalMessageSectionLink extends MessageSectionLink {
   }
 
   get text() {
-    return I18n.t(`sidebar.sections.messages.links.${this.type}`);
+    if (this.count > 0) {
+      return I18n.t(`sidebar.sections.messages.links.${this.type}_with_count`, {
+        count: this.count,
+      });
+    } else {
+      return I18n.t(`sidebar.sections.messages.links.${this.type}`);
+    }
   }
 
   pageChanged({ currentRouteName, privateMessageTopic }) {
diff --git a/app/assets/javascripts/discourse/app/models/private-message-topic-tracking-state.js b/app/assets/javascripts/discourse/app/models/private-message-topic-tracking-state.js
index 5a96b7064f4..1c95bbfcaa8 100644
--- a/app/assets/javascripts/discourse/app/models/private-message-topic-tracking-state.js
+++ b/app/assets/javascripts/discourse/app/models/private-message-topic-tracking-state.js
@@ -1,3 +1,5 @@
+import { Promise } from "rsvp";
+
 import EmberObject from "@ember/object";
 import { ajax } from "discourse/lib/ajax";
 import { bind, on } from "discourse-common/utils/decorators";
@@ -25,16 +27,20 @@ const PrivateMessageTopicTrackingState = EmberObject.extend({
     this.statesModificationCounter = 0;
     this.isTracking = false;
     this.newIncoming = [];
-    this.stateChangeCallbacks = {};
+    this.stateChangeCallbacks = new Map();
   },
 
-  onStateChange(name, callback) {
-    this.stateChangeCallbacks[name] = callback;
+  onStateChange(key, callback) {
+    this.stateChangeCallbacks.set(key, callback);
+  },
+
+  offStateChange(key) {
+    this.stateChangeCallbacks.delete(key);
   },
 
   startTracking() {
     if (this.isTracking) {
-      return;
+      return Promise.resolve();
     }
 
     this._establishChannels();
@@ -46,13 +52,13 @@ const PrivateMessageTopicTrackingState = EmberObject.extend({
 
   _establishChannels() {
     this.messageBus.subscribe(
-      this._userChannel(),
+      this.userChannel(),
       this._processMessage.bind(this)
     );
 
     this.currentUser.groupsWithMessages?.forEach((group) => {
       this.messageBus.subscribe(
-        this._groupChannel(group.id),
+        this.groupChannel(group.id),
         this._processMessage.bind(this)
       );
     });
@@ -111,11 +117,11 @@ const PrivateMessageTopicTrackingState = EmberObject.extend({
     return this.states.get(topicId);
   },
 
-  _userChannel() {
+  userChannel() {
     return `${this.CHANNEL_PREFIX}/user/${this.currentUser.id}`;
   },
 
-  _groupChannel(groupId) {
+  groupChannel(groupId) {
     return `${this.CHANNEL_PREFIX}/group/${groupId}`;
   },
 
@@ -263,7 +269,7 @@ const PrivateMessageTopicTrackingState = EmberObject.extend({
 
   _afterStateChange() {
     this.incrementProperty("statesModificationCounter");
-    Object.values(this.stateChangeCallbacks).forEach((callback) => callback());
+    this.stateChangeCallbacks.forEach((callback) => callback());
   },
 });
 
diff --git a/app/assets/javascripts/discourse/tests/acceptance/sidebar-messages-section-test.js b/app/assets/javascripts/discourse/tests/acceptance/sidebar-messages-section-test.js
index 1b293afc886..4d6770a665d 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/sidebar-messages-section-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/sidebar-messages-section-test.js
@@ -1,13 +1,17 @@
 import { test } from "qunit";
+import I18n from "I18n";
 
-import { click, currentURL, visit } from "@ember/test-helpers";
+import { click, currentURL, settled, visit } from "@ember/test-helpers";
 
 import {
   acceptance,
   exists,
+  publishToMessageBus,
+  query,
   queryAll,
   updateCurrentUser,
 } from "discourse/tests/helpers/qunit-helpers";
+import { NotificationLevels } from "discourse/lib/notification-levels";
 
 acceptance(
   "Sidebar - Messages Section - enable_personal_messages disabled",
@@ -355,5 +359,192 @@ acceptance(
         "foo_group messages inbox filter links are not shown"
       );
     });
+
+    test("new and unread counts for group messages", async function (assert) {
+      updateCurrentUser({
+        groups: [
+          {
+            id: 1,
+            name: "group1",
+            has_messages: true,
+          },
+        ],
+      });
+
+      await visit("/");
+
+      const pmTopicTrackingState = this.container.lookup(
+        "pm-topic-tracking-state:main"
+      );
+
+      publishToMessageBus(pmTopicTrackingState.groupChannel(1), {
+        topic_id: 1,
+        message_type: "unread",
+        payload: {
+          last_read_post_number: 1,
+          highest_post_number: 2,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [1],
+        },
+      });
+
+      publishToMessageBus(pmTopicTrackingState.groupChannel(1), {
+        topic_id: 2,
+        message_type: "new_topic",
+        payload: {
+          last_read_post_number: null,
+          highest_post_number: 1,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [1],
+        },
+      });
+
+      await click(
+        ".sidebar-section-messages .sidebar-section-link-group-messages-inbox.group1"
+      );
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-group-messages-unread.group1"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.unread_with_count", {
+          count: 1,
+        }),
+        "displays 1 count for group1 unread inbox filter link"
+      );
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-group-messages-new.group1"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.new_with_count", {
+          count: 1,
+        }),
+        "displays 1 count for group1 new inbox filter link"
+      );
+
+      publishToMessageBus(pmTopicTrackingState.groupChannel(1), {
+        topic_id: 2,
+        message_type: "read",
+        payload: {
+          last_read_post_number: 1,
+          highest_post_number: 1,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [1],
+        },
+      });
+
+      await settled();
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-group-messages-new.group1"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.new"),
+        "removes count for group1 new inbox filter link"
+      );
+    });
+
+    test("new and unread counts for personal messages", async function (assert) {
+      await visit("/");
+
+      const pmTopicTrackingState = this.container.lookup(
+        "pm-topic-tracking-state:main"
+      );
+
+      publishToMessageBus(pmTopicTrackingState.userChannel(), {
+        topic_id: 1,
+        message_type: "unread",
+        payload: {
+          last_read_post_number: 1,
+          highest_post_number: 2,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [],
+        },
+      });
+
+      await settled();
+
+      await click(
+        ".sidebar-section-messages .sidebar-section-link-personal-messages-inbox"
+      );
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-personal-messages-unread"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.unread_with_count", {
+          count: 1,
+        }),
+        "displays 1 count for the unread inbox filter link"
+      );
+
+      publishToMessageBus(pmTopicTrackingState.userChannel(), {
+        topic_id: 2,
+        message_type: "unread",
+        payload: {
+          last_read_post_number: 1,
+          highest_post_number: 2,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [],
+        },
+      });
+
+      await settled();
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-personal-messages-unread"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.unread_with_count", {
+          count: 2,
+        }),
+        "displays 2 count for the unread inbox filter link"
+      );
+
+      publishToMessageBus(pmTopicTrackingState.userChannel(), {
+        topic_id: 3,
+        message_type: "new_topic",
+        payload: {
+          last_read_post_number: null,
+          highest_post_number: 1,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [],
+        },
+      });
+
+      await settled();
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-personal-messages-new"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.new_with_count", {
+          count: 1,
+        }),
+        "displays 1 count for the new inbox filter link"
+      );
+
+      publishToMessageBus(pmTopicTrackingState.userChannel(), {
+        topic_id: 3,
+        message_type: "read",
+        payload: {
+          last_read_post_number: 1,
+          highest_post_number: 1,
+          notification_level: NotificationLevels.TRACKING,
+          group_ids: [],
+        },
+      });
+
+      await settled();
+
+      assert.strictEqual(
+        query(
+          ".sidebar-section-messages .sidebar-section-link-personal-messages-new"
+        ).textContent.trim(),
+        I18n.t("sidebar.sections.messages.links.new"),
+        "removes the count from the new inbox filter link"
+      );
+    });
   }
 );
diff --git a/config/locales/client.en.yml b/config/locales/client.en.yml
index a18024bd71d..7838f313de0 100644
--- a/config/locales/client.en.yml
+++ b/config/locales/client.en.yml
@@ -4051,7 +4051,9 @@ en:
             inbox: "Inbox"
             sent: "Sent"
             new: "New"
+            new_with_count: "New (%{count})"
             unread: "Unread"
+            unread_with_count: "Unread (%{count})"
             archive: "Archive"
         tags:
           no_tracked_tags: "You are not tracking any tags."