diff --git a/extensions/msteams/src/mentions.test.ts b/extensions/msteams/src/mentions.test.ts
index bfd66873ed..13d9e02e74 100644
--- a/extensions/msteams/src/mentions.test.ts
+++ b/extensions/msteams/src/mentions.test.ts
@@ -208,4 +208,16 @@ describe("formatMentionText", () => {
 
     expect(result).toBe("Hello world");
   });
+
+  it("escapes regex metacharacters in names", () => {
+    const text = "Hey @John(Test) and @Alice.Smith";
+    const mentions = [
+      { id: "28:xxx", name: "John(Test)" },
+      { id: "28:yyy", name: "Alice.Smith" },
+    ];
+
+    const result = formatMentionText(text, mentions);
+
+    expect(result).toBe("Hey <at>John(Test)</at> and <at>Alice.Smith</at>");
+  });
 });
diff --git a/extensions/msteams/src/mentions.ts b/extensions/msteams/src/mentions.ts
index 7ff3a3578e..fc63093b00 100644
--- a/extensions/msteams/src/mentions.ts
+++ b/extensions/msteams/src/mentions.ts
@@ -106,7 +106,8 @@ export function formatMentionText(text: string, mentions: MentionInfo[]): string
   let formatted = text;
   for (const mention of mentions) {
     // Replace @Name or @name with <at>Name</at>
-    const namePattern = new RegExp(`@${mention.name}`, "gi");
+    const escapedName = mention.name.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
+    const namePattern = new RegExp(`@${escapedName}`, "gi");
     formatted = formatted.replace(namePattern, `<at>${mention.name}</at>`);
   }
   return formatted;