diff --git a/extensions/msteams/src/mentions.test.ts b/extensions/msteams/src/mentions.test.ts
new file mode 100644
index 000000000..bfd66873e
--- /dev/null
+++ b/extensions/msteams/src/mentions.test.ts
@@ -0,0 +1,211 @@
+import { describe, expect, it } from "vitest";
+import { buildMentionEntities, formatMentionText, parseMentions } from "./mentions.js";
+
+describe("parseMentions", () => {
+  it("parses single mention", () => {
+    const result = parseMentions("Hello @[John Doe](28:a1b2c3-d4e5f6)!");
+
+    expect(result.text).toBe("Hello <at>John Doe</at>!");
+    expect(result.entities).toHaveLength(1);
+    expect(result.entities[0]).toEqual({
+      type: "mention",
+      text: "<at>John Doe</at>",
+      mentioned: {
+        id: "28:a1b2c3-d4e5f6",
+        name: "John Doe",
+      },
+    });
+  });
+
+  it("parses multiple mentions", () => {
+    const result = parseMentions("Hey @[Alice](28:aaa) and @[Bob](28:bbb), can you review this?");
+
+    expect(result.text).toBe("Hey <at>Alice</at> and <at>Bob</at>, can you review this?");
+    expect(result.entities).toHaveLength(2);
+    expect(result.entities[0]).toEqual({
+      type: "mention",
+      text: "<at>Alice</at>",
+      mentioned: {
+        id: "28:aaa",
+        name: "Alice",
+      },
+    });
+    expect(result.entities[1]).toEqual({
+      type: "mention",
+      text: "<at>Bob</at>",
+      mentioned: {
+        id: "28:bbb",
+        name: "Bob",
+      },
+    });
+  });
+
+  it("handles text without mentions", () => {
+    const result = parseMentions("Hello world!");
+
+    expect(result.text).toBe("Hello world!");
+    expect(result.entities).toHaveLength(0);
+  });
+
+  it("handles empty text", () => {
+    const result = parseMentions("");
+
+    expect(result.text).toBe("");
+    expect(result.entities).toHaveLength(0);
+  });
+
+  it("handles mention with spaces in name", () => {
+    const result = parseMentions("@[John Peter Smith](28:a1b2c3)");
+
+    expect(result.text).toBe("<at>John Peter Smith</at>");
+    expect(result.entities[0]?.mentioned.name).toBe("John Peter Smith");
+  });
+
+  it("trims whitespace from id and name", () => {
+    const result = parseMentions("@[ John Doe ]( 28:a1b2c3 )");
+
+    expect(result.entities[0]).toEqual({
+      type: "mention",
+      text: "<at>John Doe</at>",
+      mentioned: {
+        id: "28:a1b2c3",
+        name: "John Doe",
+      },
+    });
+  });
+
+  it("handles Japanese characters in mention at start of message", () => {
+    const input = "@[タナカ タロウ](a1b2c3d4-e5f6-7890-abcd-ef1234567890) スキル化完了しました！";
+    const result = parseMentions(input);
+
+    expect(result.text).toBe("<at>タナカ タロウ</at> スキル化完了しました！");
+    expect(result.entities).toHaveLength(1);
+    expect(result.entities[0]).toEqual({
+      type: "mention",
+      text: "<at>タナカ タロウ</at>",
+      mentioned: {
+        id: "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
+        name: "タナカ タロウ",
+      },
+    });
+
+    // Verify entity text exactly matches what's in the formatted text
+    const entityText = result.entities[0]?.text;
+    expect(result.text).toContain(entityText);
+    expect(result.text.indexOf(entityText)).toBe(0);
+  });
+
+  it("skips mention-like patterns with non-Teams IDs (e.g. in code blocks)", () => {
+    // This reproduces the actual failing payload: the message contains a real mention
+    // plus `@[表示名](ユーザーID)` as documentation text inside backticks.
+    const input =
+      "@[タナカ タロウ](a1b2c3d4-e5f6-7890-abcd-ef1234567890) スキル化完了しました！📋\n\n" +
+      "**作成したスキル:** `teams-mention`\n" +
+      "- 機能: Teamsでのメンション形式 `@[表示名](ユーザーID)`\n\n" +
+      "**追加対応:**\n" +
+      "- ユーザーのID `a1b2c3d4-e5f6-7890-abcd-ef1234567890` を登録済み";
+    const result = parseMentions(input);
+
+    // Only the real mention should be parsed; the documentation example should be left as-is
+    expect(result.entities).toHaveLength(1);
+    expect(result.entities[0]?.mentioned.id).toBe("a1b2c3d4-e5f6-7890-abcd-ef1234567890");
+    expect(result.entities[0]?.mentioned.name).toBe("タナカ タロウ");
+
+    // The documentation pattern must remain untouched in the text
+    expect(result.text).toContain("`@[表示名](ユーザーID)`");
+  });
+
+  it("accepts Bot Framework IDs (28:xxx)", () => {
+    const result = parseMentions("@[Bot](28:abc-123)");
+    expect(result.entities).toHaveLength(1);
+    expect(result.entities[0]?.mentioned.id).toBe("28:abc-123");
+  });
+
+  it("accepts AAD object IDs (UUIDs)", () => {
+    const result = parseMentions("@[User](a1b2c3d4-e5f6-7890-abcd-ef1234567890)");
+    expect(result.entities).toHaveLength(1);
+    expect(result.entities[0]?.mentioned.id).toBe("a1b2c3d4-e5f6-7890-abcd-ef1234567890");
+  });
+
+  it("rejects non-ID strings as mention targets", () => {
+    const result = parseMentions("See @[docs](https://example.com) for details");
+    expect(result.entities).toHaveLength(0);
+    // Original text preserved
+    expect(result.text).toBe("See @[docs](https://example.com) for details");
+  });
+});
+
+describe("buildMentionEntities", () => {
+  it("builds entities from mention info", () => {
+    const mentions = [
+      { id: "28:aaa", name: "Alice" },
+      { id: "28:bbb", name: "Bob" },
+    ];
+
+    const entities = buildMentionEntities(mentions);
+
+    expect(entities).toHaveLength(2);
+    expect(entities[0]).toEqual({
+      type: "mention",
+      text: "<at>Alice</at>",
+      mentioned: {
+        id: "28:aaa",
+        name: "Alice",
+      },
+    });
+    expect(entities[1]).toEqual({
+      type: "mention",
+      text: "<at>Bob</at>",
+      mentioned: {
+        id: "28:bbb",
+        name: "Bob",
+      },
+    });
+  });
+
+  it("handles empty list", () => {
+    const entities = buildMentionEntities([]);
+    expect(entities).toHaveLength(0);
+  });
+});
+
+describe("formatMentionText", () => {
+  it("formats text with single mention", () => {
+    const text = "Hello @John!";
+    const mentions = [{ id: "28:xxx", name: "John" }];
+
+    const result = formatMentionText(text, mentions);
+
+    expect(result).toBe("Hello <at>John</at>!");
+  });
+
+  it("formats text with multiple mentions", () => {
+    const text = "Hey @Alice and @Bob";
+    const mentions = [
+      { id: "28:aaa", name: "Alice" },
+      { id: "28:bbb", name: "Bob" },
+    ];
+
+    const result = formatMentionText(text, mentions);
+
+    expect(result).toBe("Hey <at>Alice</at> and <at>Bob</at>");
+  });
+
+  it("handles case-insensitive matching", () => {
+    const text = "Hey @alice and @ALICE";
+    const mentions = [{ id: "28:aaa", name: "Alice" }];
+
+    const result = formatMentionText(text, mentions);
+
+    expect(result).toBe("Hey <at>Alice</at> and <at>Alice</at>");
+  });
+
+  it("handles text without mentions", () => {
+    const text = "Hello world";
+    const mentions = [{ id: "28:xxx", name: "John" }];
+
+    const result = formatMentionText(text, mentions);
+
+    expect(result).toBe("Hello world");
+  });
+});
diff --git a/extensions/msteams/src/mentions.ts b/extensions/msteams/src/mentions.ts
new file mode 100644
index 000000000..7ff3a3578
--- /dev/null
+++ b/extensions/msteams/src/mentions.ts
@@ -0,0 +1,113 @@
+/**
+ * MS Teams mention handling utilities.
+ *
+ * Mentions in Teams require:
+ * 1. Text containing <at>Name</at> tags
+ * 2. entities array with mention metadata
+ */
+
+export type MentionEntity = {
+  type: "mention";
+  text: string;
+  mentioned: {
+    id: string;
+    name: string;
+  };
+};
+
+export type MentionInfo = {
+  /** User/bot ID (e.g., "28:xxx" or AAD object ID) */
+  id: string;
+  /** Display name */
+  name: string;
+};
+
+/**
+ * Check whether an ID looks like a valid Teams user/bot identifier.
+ * Accepts:
+ * - Bot Framework IDs: "28:xxx..." or "29:xxx..."
+ * - AAD object IDs (UUIDs): "d5318c29-33ac-4e6b-bd42-57b8b793908f"
+ *
+ * This prevents false positives from text like `@[表示名](ユーザーID)`
+ * that appears in code snippets or documentation within messages.
+ */
+const TEAMS_ID_PATTERN =
+  /^(?:\d+:[a-f0-9-]+|[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12})$/i;
+
+function isValidTeamsId(id: string): boolean {
+  return TEAMS_ID_PATTERN.test(id);
+}
+
+/**
+ * Parse mentions from text in the format @[Name](id).
+ * Example: "Hello @[John Doe](28:xxx-yyy-zzz)!"
+ *
+ * Only matches where the id looks like a real Teams user/bot ID are treated
+ * as mentions. This avoids false positives from documentation or code samples
+ * embedded in the message (e.g. `@[表示名](ユーザーID)` in backticks).
+ *
+ * Returns both the formatted text with <at> tags and the entities array.
+ */
+export function parseMentions(text: string): {
+  text: string;
+  entities: MentionEntity[];
+} {
+  const mentionPattern = /@\[([^\]]+)\]\(([^)]+)\)/g;
+  const entities: MentionEntity[] = [];
+
+  // Replace @[Name](id) with <at>Name</at> only for valid Teams IDs
+  const formattedText = text.replace(mentionPattern, (match, name, id) => {
+    const trimmedId = id.trim();
+
+    // Skip matches where the id doesn't look like a real Teams identifier
+    if (!isValidTeamsId(trimmedId)) {
+      return match;
+    }
+
+    const trimmedName = name.trim();
+    const mentionTag = `<at>${trimmedName}</at>`;
+    entities.push({
+      type: "mention",
+      text: mentionTag,
+      mentioned: {
+        id: trimmedId,
+        name: trimmedName,
+      },
+    });
+    return mentionTag;
+  });
+
+  return {
+    text: formattedText,
+    entities,
+  };
+}
+
+/**
+ * Build mention entities array from a list of mentions.
+ * Use this when you already have the mention info and formatted text.
+ */
+export function buildMentionEntities(mentions: MentionInfo[]): MentionEntity[] {
+  return mentions.map((mention) => ({
+    type: "mention",
+    text: `<at>${mention.name}</at>`,
+    mentioned: {
+      id: mention.id,
+      name: mention.name,
+    },
+  }));
+}
+
+/**
+ * Format text with mentions using <at> tags.
+ * This is a convenience function when you want to manually format mentions.
+ */
+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(`@${mention.name}`, "gi");
+    formatted = formatted.replace(namePattern, `<at>${mention.name}</at>`);
+  }
+  return formatted;
+}
diff --git a/extensions/msteams/src/messenger.ts b/extensions/msteams/src/messenger.ts
index 11b04db8e..e29c620b2 100644
--- a/extensions/msteams/src/messenger.ts
+++ b/extensions/msteams/src/messenger.ts
@@ -19,6 +19,7 @@ import {
   uploadAndShareSharePoint,
 } from "./graph-upload.js";
 import { extractFilename, extractMessageId, getMimeType, isLocalPath } from "./media-helpers.js";
+import { parseMentions } from "./mentions.js";
 import { getMSTeamsRuntime } from "./runtime.js";
 
 /**
@@ -269,7 +270,14 @@ async function buildActivity(
   const activity: Record<string, unknown> = { type: "message" };
 
   if (msg.text) {
-    activity.text = msg.text;
+    // Parse mentions from text (format: @[Name](id))
+    const { text: formattedText, entities } = parseMentions(msg.text);
+    activity.text = formattedText;
+
+    // Add mention entities if any mentions were found
+    if (entities.length > 0) {
+      activity.entities = entities;
+    }
   }
 
   if (msg.mediaUrl) {