diff --git a/addons/im_livechat/static/src/core/web/suggestion_service_patch.js b/addons/im_livechat/static/src/core/web/suggestion_service_patch.js
index f312cf2bbd7..9cfd68bdf9a 100644
--- a/addons/im_livechat/static/src/core/web/suggestion_service_patch.js
+++ b/addons/im_livechat/static/src/core/web/suggestion_service_patch.js
@@ -11,8 +11,15 @@ patch(SuggestionService.prototype, {
             ? [...super.getSupportedDelimiters(...arguments), [":"]]
             : super.getSupportedDelimiters(...arguments);
     },
+    async fetchSuggestions({ delimiter, term }, { thread } = {}) {
+        if (thread.type === "livechat" && delimiter === "#") {
+            return;
+        }
+        return super.fetchSuggestions(...arguments);
+    },
     /**
      * Returns suggestions that match the given search term from specified type.
+     * Searching on channels is disabled in livechat since the visitor don't have access to channels.
      *
      * @param {Object} [param0={}]
      * @param {String} [param0.delimiter] can be one one of the following: ["@", ":", "#", "/"]
@@ -23,6 +30,13 @@ patch(SuggestionService.prototype, {
      * @returns {[mainSuggestion[], extraSuggestion[]]}
      */
     searchSuggestions({ delimiter, term }, { thread } = {}, sort = false) {
+        if (thread.type === "livechat" && delimiter === "#") {
+            return {
+                type: undefined,
+                mainSuggestions: [],
+                extraSuggestions: [],
+            };
+        }
         if (delimiter === ":") {
             return this.searchCannedResponseSuggestions(cleanTerm(term), sort);
         }
diff --git a/addons/im_livechat/static/tests/suggestions_tests.js b/addons/im_livechat/static/tests/suggestions_tests.js
index b95418f5ed1..70c16972e82 100644
--- a/addons/im_livechat/static/tests/suggestions_tests.js
+++ b/addons/im_livechat/static/tests/suggestions_tests.js
@@ -32,3 +32,26 @@ QUnit.test("Suggestions are shown after delimiter was used in text (:)", async (
     await insertText(".o-mail-Composer-input", " :");
     await contains(".o-mail-Composer-suggestion strong", { text: "hello" });
 });
+
+QUnit.test("Cannot mention other channels in a livechat", async () => {
+    const pyEnv = await startServer();
+    const [channelId] = pyEnv["discuss.channel"].create([
+        {
+            anonymous_name: "Visitor",
+            channel_type: "livechat",
+            channel_member_ids: [
+                Command.create({ partner_id: pyEnv.currentPartnerId }),
+                Command.create({ partner_id: pyEnv.publicPartnerId }),
+            ],
+        },
+        {
+            channel_type: "channel",
+            group_public_id: false,
+            name: "Link and Zelda",
+        },
+    ]);
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    await insertText(".o-mail-Composer-input", "#");
+    await contains(".o-mail-Composer-suggestion", { count: 0 });
+});
diff --git a/addons/mail/static/src/core/common/suggestion_service.js b/addons/mail/static/src/core/common/suggestion_service.js
index 14d50508e11..5b75e4952ab 100644
--- a/addons/mail/static/src/core/common/suggestion_service.js
+++ b/addons/mail/static/src/core/common/suggestion_service.js
@@ -85,7 +85,7 @@ export class SuggestionService {
                 return this.searchPartnerSuggestions(cleanedSearchTerm, thread, sort);
             }
             case "#":
-                return this.searchChannelSuggestions(cleanedSearchTerm, thread, sort);
+                return this.searchChannelSuggestions(cleanedSearchTerm, sort);
         }
         return {
             type: undefined,
@@ -168,24 +168,8 @@ export class SuggestionService {
         });
     }
 
-    searchChannelSuggestions(cleanedSearchTerm, thread, sort) {
-        let threads;
-        if (
-            thread &&
-            (thread.type === "group" ||
-                thread.type === "chat" ||
-                (thread.type === "channel" && thread.authorizedGroupFullName))
-        ) {
-            // Only return the current channel when in the context of a
-            // group restricted channel or group or chat. Indeed, the message with the mention
-            // would appear in the target channel, so this prevents from
-            // inadvertently leaking the private message into the mentioned
-            // channel.
-            threads = [thread];
-        } else {
-            threads = Object.values(this.store.Thread.records);
-        }
-        const suggestionList = threads.filter(
+    searchChannelSuggestions(cleanedSearchTerm, sort) {
+        const suggestionList = Object.values(this.store.Thread.records).filter(
             (thread) =>
                 thread.type === "channel" &&
                 thread.displayName &&
diff --git a/addons/mail/static/tests/thread/thread_tests.js b/addons/mail/static/tests/thread/thread_tests.js
index 0aa8b5a82ce..11eb6db060e 100644
--- a/addons/mail/static/tests/thread/thread_tests.js
+++ b/addons/mail/static/tests/thread/thread_tests.js
@@ -213,6 +213,34 @@ QUnit.test("thread is still scrolling after scrolling up then to bottom", async
     await contains(".o-mail-Thread", { scroll: "bottom" });
 });
 
+QUnit.test("Can mention other channels in a group-restricted channel", async () => {
+    const pyEnv = await startServer();
+    const groupId = pyEnv["res.groups"].create({
+        name: "Mario Group",
+    });
+    const [channelId1] = pyEnv["discuss.channel"].create([
+        {
+            channel_type: "channel",
+            group_public_id: groupId,
+            name: "Marios",
+        },
+        {
+            channel_type: "channel",
+            group_public_id: false,
+            name: "Link and Zelda",
+        },
+    ]);
+    const { openDiscuss } = await start();
+    openDiscuss(channelId1);
+    await insertText(".o-mail-Composer-input", "#");
+    await contains(".o-mail-Composer-suggestion", { text: "#Marios" });
+    await contains(".o-mail-Composer-suggestion", { text: "#Link and Zelda" });
+    await click(".o-mail-Composer-suggestion", { text: "#Link and Zelda" });
+    await contains(".o-mail-Composer-input", { value: "#Link and Zelda " });
+    await click(".o-mail-Composer-send:enabled");
+    await contains(".o-mail-Message-body .o_channel_redirect", { text: "#Link and Zelda" });
+});
+
 QUnit.test("mention a channel with space in the name", async () => {
     const pyEnv = await startServer();
     const channelId = pyEnv["discuss.channel"].create({ name: "General good boy" });