diff --git a/apps/sim/app/api/tools/microsoft_teams/write_channel/route.ts b/apps/sim/app/api/tools/microsoft_teams/write_channel/route.ts
index ef56d496b7..fad1296281 100644
--- a/apps/sim/app/api/tools/microsoft_teams/write_channel/route.ts
+++ b/apps/sim/app/api/tools/microsoft_teams/write_channel/route.ts
@@ -4,6 +4,7 @@ import { checkHybridAuth } from '@/lib/auth/hybrid'
 import { createLogger } from '@/lib/logs/console/logger'
 import { downloadFileFromStorage, processFilesToUserFiles } from '@/lib/uploads/file-processing'
 import { generateRequestId } from '@/lib/utils'
+import { resolveMentionsForChannel } from '@/tools/microsoft_teams/utils'
 
 export const dynamic = 'force-dynamic'
 
@@ -140,23 +141,62 @@ export async function POST(request: NextRequest) {
     }
 
     let messageContent = validatedData.content
+    let contentType: 'text' | 'html' = 'text'
+    const mentionEntities: Array<{
+      type: 'mention'
+      mentioned: { id: string; name: string }
+      text: string
+    }> = []
+
+    try {
+      const mentionResult = await resolveMentionsForChannel(
+        validatedData.content,
+        validatedData.teamId,
+        validatedData.channelId,
+        validatedData.accessToken
+      )
+
+      if (mentionResult.hasMentions) {
+        contentType = 'html'
+        mentionEntities.push(...mentionResult.entities)
+        logger.info(`[${requestId}] Resolved ${mentionResult.entities.length} mention(s)`)
+      }
+    } catch (error) {
+      logger.warn(`[${requestId}] Failed to resolve mentions, continuing without them:`, error)
+    }
 
     if (attachments.length > 0) {
+      contentType = 'html'
       const attachmentTags = attachments
         .map((att) => `<attachment id="${att.id}"></attachment>`)
         .join(' ')
       messageContent = `${validatedData.content}<br/>${attachmentTags}`
     }
 
-    const messageBody = {
+    const messageBody: {
       body: {
-        contentType: attachments.length > 0 ? 'html' : 'text',
+        contentType: 'text' | 'html'
+        content: string
+      }
+      attachments?: any[]
+      mentions?: Array<{
+        type: 'mention'
+        mentioned: { id: string; name: string }
+        text: string
+      }>
+    } = {
+      body: {
+        contentType,
         content: messageContent,
       },
     }
 
     if (attachments.length > 0) {
-      ;(messageBody as any).attachments = attachments
+      messageBody.attachments = attachments
+    }
+
+    if (mentionEntities.length > 0) {
+      messageBody.mentions = mentionEntities
     }
 
     logger.info(`[${requestId}] Sending message to Teams channel: ${validatedData.channelId}`)
diff --git a/apps/sim/app/api/tools/microsoft_teams/write_chat/route.ts b/apps/sim/app/api/tools/microsoft_teams/write_chat/route.ts
index f7dd519760..445edf480c 100644
--- a/apps/sim/app/api/tools/microsoft_teams/write_chat/route.ts
+++ b/apps/sim/app/api/tools/microsoft_teams/write_chat/route.ts
@@ -4,6 +4,7 @@ import { checkHybridAuth } from '@/lib/auth/hybrid'
 import { createLogger } from '@/lib/logs/console/logger'
 import { downloadFileFromStorage, processFilesToUserFiles } from '@/lib/uploads/file-processing'
 import { generateRequestId } from '@/lib/utils'
+import { resolveMentionsForChat } from '@/tools/microsoft_teams/utils'
 
 export const dynamic = 'force-dynamic'
 
@@ -138,23 +139,61 @@ export async function POST(request: NextRequest) {
     }
 
     let messageContent = validatedData.content
+    let contentType: 'text' | 'html' = 'text'
+    const mentionEntities: Array<{
+      type: 'mention'
+      mentioned: { id: string; name: string }
+      text: string
+    }> = []
+
+    try {
+      const mentionResult = await resolveMentionsForChat(
+        validatedData.content,
+        validatedData.chatId,
+        validatedData.accessToken
+      )
+
+      if (mentionResult.hasMentions) {
+        contentType = 'html'
+        mentionEntities.push(...mentionResult.entities)
+        logger.info(`[${requestId}] Resolved ${mentionResult.entities.length} mention(s)`)
+      }
+    } catch (error) {
+      logger.warn(`[${requestId}] Failed to resolve mentions, continuing without them:`, error)
+    }
 
     if (attachments.length > 0) {
+      contentType = 'html'
       const attachmentTags = attachments
         .map((att) => `<attachment id="${att.id}"></attachment>`)
         .join(' ')
       messageContent = `${validatedData.content}<br/>${attachmentTags}`
     }
 
-    const messageBody = {
+    const messageBody: {
       body: {
-        contentType: attachments.length > 0 ? 'html' : 'text',
+        contentType: 'text' | 'html'
+        content: string
+      }
+      attachments?: any[]
+      mentions?: Array<{
+        type: 'mention'
+        mentioned: { id: string; name: string }
+        text: string
+      }>
+    } = {
+      body: {
+        contentType,
         content: messageContent,
       },
     }
 
     if (attachments.length > 0) {
-      ;(messageBody as any).attachments = attachments
+      messageBody.attachments = attachments
+    }
+
+    if (mentionEntities.length > 0) {
+      messageBody.mentions = mentionEntities
     }
 
     logger.info(`[${requestId}] Sending message to Teams chat: ${validatedData.chatId}`)
diff --git a/apps/sim/tools/microsoft_teams/utils.ts b/apps/sim/tools/microsoft_teams/utils.ts
index 27e25489dc..20b6939318 100644
--- a/apps/sim/tools/microsoft_teams/utils.ts
+++ b/apps/sim/tools/microsoft_teams/utils.ts
@@ -4,6 +4,28 @@ import type { ToolFileData } from '@/tools/types'
 
 const logger = createLogger('MicrosoftTeamsUtils')
 
+interface ParsedMention {
+  name: string
+  fullTag: string
+  startIndex: number
+  endIndex: number
+}
+
+interface TeamMember {
+  id: string
+  displayName: string
+  userIdentityType?: string
+}
+
+export interface MentionEntity {
+  type: 'mention'
+  mentioned: {
+    id: string
+    name: string
+  }
+  text: string
+}
+
 /**
  * Transform raw attachment data from Microsoft Graph API
  */
@@ -99,3 +121,161 @@ export async function fetchHostedContentsForChannelMessage(params: {
     return []
   }
 }
+
+function parseMentions(content: string): ParsedMention[] {
+  const mentions: ParsedMention[] = []
+  const mentionRegex = /<at>([^<]+)<\/at>/gi
+  let match: RegExpExecArray | null
+
+  while ((match = mentionRegex.exec(content)) !== null) {
+    const name = match[1].trim()
+    if (name) {
+      mentions.push({
+        name,
+        fullTag: match[0],
+        startIndex: match.index,
+        endIndex: match.index + match[0].length,
+      })
+    }
+  }
+
+  return mentions
+}
+
+async function fetchChatMembers(chatId: string, accessToken: string): Promise<TeamMember[]> {
+  const response = await fetch(
+    `https://graph.microsoft.com/v1.0/chats/${encodeURIComponent(chatId)}/members`,
+    {
+      headers: {
+        Authorization: `Bearer ${accessToken}`,
+        'Content-Type': 'application/json',
+      },
+    }
+  )
+
+  if (!response.ok) {
+    return []
+  }
+
+  const data = await response.json()
+  return (data.value || []).map((member: TeamMember) => ({
+    id: member.id,
+    displayName: member.displayName || '',
+    userIdentityType: member.userIdentityType,
+  }))
+}
+
+async function fetchChannelMembers(
+  teamId: string,
+  channelId: string,
+  accessToken: string
+): Promise<TeamMember[]> {
+  const response = await fetch(
+    `https://graph.microsoft.com/v1.0/teams/${encodeURIComponent(teamId)}/channels/${encodeURIComponent(channelId)}/members`,
+    {
+      headers: {
+        Authorization: `Bearer ${accessToken}`,
+        'Content-Type': 'application/json',
+      },
+    }
+  )
+
+  if (!response.ok) {
+    return []
+  }
+
+  const data = await response.json()
+  return (data.value || []).map((member: TeamMember) => ({
+    id: member.id,
+    displayName: member.displayName || '',
+    userIdentityType: member.userIdentityType,
+  }))
+}
+
+function findMemberByName(members: TeamMember[], name: string): TeamMember | undefined {
+  const normalizedName = name.trim().toLowerCase()
+  return members.find((member) => member.displayName.toLowerCase() === normalizedName)
+}
+
+export async function resolveMentionsForChat(
+  content: string,
+  chatId: string,
+  accessToken: string
+): Promise<{ entities: MentionEntity[]; hasMentions: boolean }> {
+  const parsedMentions = parseMentions(content)
+
+  if (parsedMentions.length === 0) {
+    return { entities: [], hasMentions: false }
+  }
+
+  const members = await fetchChatMembers(chatId, accessToken)
+  const entities: MentionEntity[] = []
+  const resolvedNames = new Set<string>()
+
+  for (const mention of parsedMentions) {
+    if (resolvedNames.has(mention.fullTag)) {
+      continue
+    }
+
+    const member = findMemberByName(members, mention.name)
+
+    if (member) {
+      entities.push({
+        type: 'mention',
+        mentioned: {
+          id: member.id,
+          name: member.displayName,
+        },
+        text: mention.fullTag,
+      })
+      resolvedNames.add(mention.fullTag)
+    }
+  }
+
+  return {
+    entities,
+    hasMentions: entities.length > 0,
+  }
+}
+
+export async function resolveMentionsForChannel(
+  content: string,
+  teamId: string,
+  channelId: string,
+  accessToken: string
+): Promise<{ entities: MentionEntity[]; hasMentions: boolean }> {
+  const parsedMentions = parseMentions(content)
+
+  if (parsedMentions.length === 0) {
+    return { entities: [], hasMentions: false }
+  }
+
+  const members = await fetchChannelMembers(teamId, channelId, accessToken)
+  const entities: MentionEntity[] = []
+  const resolvedNames = new Set<string>()
+
+  for (const mention of parsedMentions) {
+    if (resolvedNames.has(mention.fullTag)) {
+      continue
+    }
+
+    const member = findMemberByName(members, mention.name)
+
+    if (member) {
+      entities.push({
+        type: 'mention',
+        mentioned: {
+          id: member.id,
+          name: member.displayName,
+        },
+        text: mention.fullTag,
+      })
+      resolvedNames.add(mention.fullTag)
+    }
+  }
+
+  return {
+    entities,
+    hasMentions: entities.length > 0,
+  }
+}
diff --git a/apps/sim/tools/microsoft_teams/write_channel.ts b/apps/sim/tools/microsoft_teams/write_channel.ts
index 043cda86d7..3b372cc323 100644
--- a/apps/sim/tools/microsoft_teams/write_channel.ts
+++ b/apps/sim/tools/microsoft_teams/write_channel.ts
@@ -73,6 +73,12 @@ export const writeChannelTool: ToolConfig<MicrosoftTeamsToolParams, MicrosoftTea
         return '/api/tools/microsoft_teams/write_channel'
       }
 
+      // If content contains mentions, use custom API route for mention resolution
+      const hasMentions = /<at>[^<]+<\/at>/i.test(params.content || '')
+      if (hasMentions) {
+        return '/api/tools/microsoft_teams/write_channel'
+      }
+
       const encodedTeamId = encodeURIComponent(teamId)
       const encodedChannelId = encodeURIComponent(channelId)
 
@@ -98,7 +104,8 @@ export const writeChannelTool: ToolConfig<MicrosoftTeamsToolParams, MicrosoftTea
         throw new Error('Content is required')
       }
 
-      // If using custom API route (with files), pass all params
+      // If using custom API route (with files or mentions), pass all params
+      const hasMentions = /<at>[^<]+<\/at>/i.test(params.content || '')
       if (params.files && params.files.length > 0) {
         return {
           accessToken: params.accessToken,
@@ -109,6 +116,15 @@ export const writeChannelTool: ToolConfig<MicrosoftTeamsToolParams, MicrosoftTea
         }
       }
 
+      if (hasMentions) {
+        return {
+          accessToken: params.accessToken,
+          teamId: params.teamId,
+          channelId: params.channelId,
+          content: params.content,
+        }
+      }
+
       // Microsoft Teams API expects this specific format for channel messages
       const requestBody = {
         body: {
diff --git a/apps/sim/tools/microsoft_teams/write_chat.ts b/apps/sim/tools/microsoft_teams/write_chat.ts
index 203b604537..ee377c3f6f 100644
--- a/apps/sim/tools/microsoft_teams/write_chat.ts
+++ b/apps/sim/tools/microsoft_teams/write_chat.ts
@@ -62,6 +62,12 @@ export const writeChatTool: ToolConfig<MicrosoftTeamsToolParams, MicrosoftTeamsW
         return '/api/tools/microsoft_teams/write_chat'
       }
 
+      // If content contains mentions, use custom API route for mention resolution
+      const hasMentions = /<at>[^<]+<\/at>/i.test(params.content || '')
+      if (hasMentions) {
+        return '/api/tools/microsoft_teams/write_chat'
+      }
+
       return `https://graph.microsoft.com/v1.0/chats/${encodeURIComponent(chatId)}/messages`
     },
     method: 'POST',
@@ -82,7 +88,8 @@ export const writeChatTool: ToolConfig<MicrosoftTeamsToolParams, MicrosoftTeamsW
         throw new Error('Content is required')
       }
 
-      // If using custom API route (with files), pass all params
+      // If using custom API route (with files or mentions), pass all params
+      const hasMentions = /<at>[^<]+<\/at>/i.test(params.content || '')
       if (params.files && params.files.length > 0) {
         return {
           accessToken: params.accessToken,
@@ -92,6 +99,14 @@ export const writeChatTool: ToolConfig<MicrosoftTeamsToolParams, MicrosoftTeamsW
         }
       }
 
+      if (hasMentions) {
+        return {
+          accessToken: params.accessToken,
+          chatId: params.chatId,
+          content: params.content,
+        }
+      }
+
       // Microsoft Teams API expects this specific format
       const requestBody = {
         body: {