diff --git a/lib/shared/mention-utils.js b/lib/shared/mention-utils.js
--- a/lib/shared/mention-utils.js
+++ b/lib/shared/mention-utils.js
@@ -5,10 +5,11 @@
 import { threadOtherMembers, chatNameMaxLength } from './thread-utils.js';
 import { stringForUserExplicit } from './user-utils.js';
 import { threadTypes } from '../types/thread-types-enum.js';
-import {
-  type ThreadInfo,
-  type RelativeMemberInfo,
-  type ResolvedThreadInfo,
+import type {
+  ThreadInfo,
+  RelativeMemberInfo,
+  ResolvedThreadInfo,
+  ChatMentionCandidates,
 } from '../types/thread-types.js';
 import { idSchemaRegex } from '../utils/validation-utils.js';
 
@@ -108,6 +109,28 @@
     .map(userInfo => ({ type: 'user', userInfo }));
 }
 
+function getMentionTypeaheadChatSuggestions(
+  chatSearchIndex: SentencePrefixSearchIndex,
+  chatMentionCandidates: ChatMentionCandidates,
+  chatNamePrefix: string,
+): $ReadOnlyArray<MentionTypeaheadChatSuggestionItem> {
+  const result = [];
+  const threadIDs =
+    chatNamePrefix.length === 0
+      ? chatSearchIndex.entries
+      : chatSearchIndex.getSearchResults(chatNamePrefix);
+  for (const threadID of threadIDs) {
+    if (!chatMentionCandidates[threadID]) {
+      continue;
+    }
+    result.push({
+      type: 'chat',
+      threadInfo: chatMentionCandidates[threadID],
+    });
+  }
+  return result;
+}
+
 function getNewTextAndSelection(
   textBeforeAtSymbol: string,
   entireText: string,
@@ -150,6 +173,7 @@
   isUserMentioned,
   extractUserMentionsFromText,
   getMentionTypeaheadUserSuggestions,
+  getMentionTypeaheadChatSuggestions,
   getNewTextAndSelection,
   getTypeaheadRegexMatches,
   getUserMentionsCandidates,
diff --git a/lib/shared/thread-utils.js b/lib/shared/thread-utils.js
--- a/lib/shared/thread-utils.js
+++ b/lib/shared/thread-utils.js
@@ -114,8 +114,8 @@
 const chatNameMaxLength = 191;
 const chatNameMinLength = 0;
 const secondCharRange = `{${chatNameMinLength},${chatNameMaxLength}}`;
-const validChatNameRegexString = `^.${secondCharRange}$`;
-const validChatNameRegex: RegExp = new RegExp(validChatNameRegexString);
+const validChatNameRegexString = `.${secondCharRange}`;
+const validChatNameRegex: RegExp = new RegExp(`^${validChatNameRegexString}$`);
 
 function threadHasPermission(
   threadInfo: ?(ThreadInfo | RawThreadInfo),
@@ -1961,6 +1961,7 @@
   getAvailableThreadMemberActions,
   threadMembersWithoutAddedAshoat,
   validChatNameRegex,
+  validChatNameRegexString,
   chatNameMaxLength,
   patchThreadInfoToIncludeMentionedMembersOfParent,
   threadInfoInsideCommunity,
diff --git a/native/avatars/thread-avatar.react.js b/native/avatars/thread-avatar.react.js
--- a/native/avatars/thread-avatar.react.js
+++ b/native/avatars/thread-avatar.react.js
@@ -8,13 +8,17 @@
 } from 'lib/shared/avatar-utils.js';
 import { getSingleOtherUser } from 'lib/shared/thread-utils.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
-import { type RawThreadInfo, type ThreadInfo } from 'lib/types/thread-types.js';
+import type {
+  RawThreadInfo,
+  ThreadInfo,
+  ResolvedThreadInfo,
+} from 'lib/types/thread-types.js';
 
 import Avatar, { type AvatarSize } from './avatar.react.js';
 import { useSelector } from '../redux/redux-utils.js';
 
 type Props = {
-  +threadInfo: RawThreadInfo | ThreadInfo,
+  +threadInfo: RawThreadInfo | ThreadInfo | ResolvedThreadInfo,
   +size: AvatarSize,
 };
 
diff --git a/native/chat/chat-input-bar.react.js b/native/chat/chat-input-bar.react.js
--- a/native/chat/chat-input-bar.react.js
+++ b/native/chat/chat-input-bar.react.js
@@ -38,6 +38,7 @@
 import { useEditMessage } from 'lib/shared/edit-messages-utils.js';
 import {
   getMentionTypeaheadUserSuggestions,
+  getMentionTypeaheadChatSuggestions,
   getTypeaheadRegexMatches,
   type Selection,
   getUserMentionsCandidates,
@@ -58,6 +59,7 @@
   checkIfDefaultMembersAreVoiced,
   draftKeyFromThreadID,
   useThreadChatMentionCandidates,
+  useThreadChatMentionSearchIndex,
 } from 'lib/shared/thread-utils.js';
 import type { CalendarQuery } from 'lib/types/entry-types.js';
 import type { LoadingStatus } from 'lib/types/loading-types.js';
@@ -74,6 +76,7 @@
   ClientThreadJoinRequest,
   ThreadJoinPayload,
   RelativeMemberInfo,
+  ChatMentionCandidates,
 } from 'lib/types/thread-types.js';
 import { type UserInfos } from 'lib/types/user-types.js';
 import {
@@ -173,6 +176,8 @@
   +inputState: ?InputState,
   +userSearchIndex: SentencePrefixSearchIndex,
   +userMentionsCandidates: $ReadOnlyArray<RelativeMemberInfo>,
+  +chatMentionSearchIndex: SentencePrefixSearchIndex,
+  +chatMentionCandidates: ChatMentionCandidates,
   +parentThreadInfo: ?ThreadInfo,
   +editedMessagePreview: ?MessagePreviewResult,
   +editedMessageInfo: ?MessageInfo,
@@ -565,13 +570,19 @@
         this.props.viewerID,
         typeaheadMatchedStrings.query,
       );
+      const suggestedChats = getMentionTypeaheadChatSuggestions(
+        this.props.chatMentionSearchIndex,
+        this.props.chatMentionCandidates,
+        typeaheadMatchedStrings.query,
+      );
+      const suggestions = [...suggestedUsers, ...suggestedChats];
 
-      if (suggestedUsers.length > 0) {
+      if (suggestions.length > 0) {
         typeaheadTooltip = (
           <TypeaheadTooltip
             text={this.state.text}
             matchedStrings={typeaheadMatchedStrings}
-            suggestions={suggestedUsers}
+            suggestions={suggestions}
             focusAndUpdateTextAndSelection={this.focusAndUpdateTextAndSelection}
             typeaheadTooltipActionsGetter={mentionTypeaheadTooltipActions}
             TypeaheadTooltipButtonComponent={MentionTypeaheadTooltipButton}
@@ -1255,6 +1266,10 @@
 
   const userSearchIndex = useSelector(userStoreMentionSearchIndex);
 
+  const chatMentionSearchIndex = useThreadChatMentionSearchIndex(
+    props.threadInfo,
+  );
+
   const { parentThreadID } = props.threadInfo;
   const parentThreadInfo = useSelector(state =>
     parentThreadID ? threadInfoSelector(state)[parentThreadID] : null,
@@ -1299,6 +1314,8 @@
       inputState={inputState}
       userSearchIndex={userSearchIndex}
       userMentionsCandidates={userMentionsCandidates}
+      chatMentionSearchIndex={chatMentionSearchIndex}
+      chatMentionCandidates={chatMentionCandidates}
       parentThreadInfo={parentThreadInfo}
       editedMessagePreview={editedMessagePreview}
       editedMessageInfo={editedMessageInfo}
diff --git a/native/chat/mention-typeahead-tooltip-button.react.js b/native/chat/mention-typeahead-tooltip-button.react.js
--- a/native/chat/mention-typeahead-tooltip-button.react.js
+++ b/native/chat/mention-typeahead-tooltip-button.react.js
@@ -8,6 +8,7 @@
   MentionTypeaheadSuggestionItem,
 } from 'lib/shared/mention-utils.js';
 
+import ThreadAvatar from '../avatars/thread-avatar.react.js';
 import UserAvatar from '../avatars/user-avatar.react.js';
 import Button from '../components/button.react.js';
 import { useStyles } from '../themes/colors.js';
@@ -26,6 +27,14 @@
       <UserAvatar size="small" userID={item.actionButtonContent.userInfo.id} />
     );
     typeaheadTooltipButtonText = item.actionButtonContent.userInfo.username;
+  } else if (item.actionButtonContent.type === 'chat') {
+    typeaheadTooltipButtonText = item.actionButtonContent.threadInfo.uiName;
+    avatarComponent = (
+      <ThreadAvatar
+        size="small"
+        threadInfo={item.actionButtonContent.threadInfo}
+      />
+    );
   }
 
   return (
diff --git a/native/utils/typeahead-utils.js b/native/utils/typeahead-utils.js
--- a/native/utils/typeahead-utils.js
+++ b/native/utils/typeahead-utils.js
@@ -2,7 +2,6 @@
 
 import * as React from 'react';
 
-import { oldValidUsernameRegexString } from 'lib/shared/account-utils.js';
 import {
   getNewTextAndSelection,
   getRawChatMention,
@@ -10,12 +9,13 @@
   type TypeaheadTooltipActionItem,
   type MentionTypeaheadSuggestionItem,
 } from 'lib/shared/mention-utils.js';
+import { validChatNameRegexString } from 'lib/shared/thread-utils.js';
 import { stringForUserExplicit } from 'lib/shared/user-utils.js';
 
 // Native regex is a little bit different than web one as
 // there are no named capturing groups yet on native.
 const nativeMentionTypeaheadRegex: RegExp = new RegExp(
-  `((^(.|\n)*\\s+)|^)@(${oldValidUsernameRegexString})?$`,
+  `((^(.|\n)*\\s+)|^)@(${validChatNameRegexString})?$`,
 );
 
 export type TypeaheadTooltipActionsParams<SuggestionItemType> = {