A Slack and Microsoft Teams integration comes in four kinds. The Microsoft Teams Calls app lets people start and join Teams meetings from Slack. Zapier can copy new messages from a channel in one app to a channel in the other. Power Automate's Slack connector can post into Slack from a flow. And Microsoft's Slack to Teams migration tool moves channel history across for good. Where it stops: none of them keeps a conversation in step both ways. Edits, deletes, direct messages and replies are left behind, and someone still copies the request across and tells the other side when it is done. AI agents do that work.
What a Slack and Microsoft Teams integration has to do
Many companies end up with both. Your team works in Slack, and a big client, a parent company or a new hire's old firm works in Teams. Or you are moving from one to the other and both run for a few months. Either way, someone reads a message in one app and retypes it in the other.
So connected has to mean something specific. Is it calls, so people can join each other's meetings? Is it messages, so a request posted in one app shows up in the other? Or is it a one time move of your history? Each of those is a different tool, and none of them does all three.
Four ways to connect Slack and Microsoft Teams
Each one does one part of the job. You may need two of them.
Microsoft Teams Calls for Slack
- How it works
- You add the Microsoft Teams Calls app from the Slack Marketplace, and each person connects their Microsoft account. Typing /teams-calls in any Slack conversation starts a Teams meeting, and everyone in the conversation sees a Join button.
- Good for
- Slack teams whose clients or suppliers hold their meetings in Teams.
- Where it breaks
- It starts and joins meetings, and that is all. No messages or files move between the apps. Slack says it doesn't support Office 365 plans on Microsoft's national clouds, and on an Enterprise plan it has to be installed in each workspace.
A Zapier zap
- How it works
- Zapier can start from Microsoft Teams, like New Channel Message or New Chat Message, and post to Slack with Send Channel Message. It can also go the other way, from Slack's New Message Posted to Channel to a Teams channel.
- Good for
- One or two channels where a client or sister company posts requests that your team has to see.
- Where it breaks
- Each direction is its own zap, and each one copies new messages only. An edit, a delete or a reply in a thread is another trigger to set up, or it doesn't come across. Slack's Send Bot Message step posts from the Zapier bot, not from the person who wrote it.
Power Automate's Slack connector
- How it works
- Microsoft's Slack connector lets a Power Automate flow post a message to a Slack channel, list a channel's messages and create channels. A flow can start from something in Teams and post it in Slack.
- Good for
- Companies on Microsoft 365 that already build flows in Power Automate.
- Where it breaks
- Microsoft's page lists one Slack trigger: When a file is created. So a flow can't start when someone posts a message in Slack. Messages are capped at 4,000 characters, and each connection is limited to 100 calls a minute.
Microsoft's Slack to Teams migration tool
- How it works
- In the Microsoft 365 admin center, the tool reads a Slack export file and moves public and private channels, threads, reactions, files and members into Teams channels you set.
- Good for
- Companies leaving Slack for Teams for good.
- Where it breaks
- Microsoft says it moves channel content only: no direct messages, group chats, workflows or app integrations. It doesn't move Slack Connect or archived channels. Later passes add only new messages, so edits, deletes and new replies to old messages are missed.
Arkeo agents
- How it works
- Agents read requests posted in the channels you set, in Slack or Teams, log each one with an owner, post it where that person works, follow up until it is done, and tell the person who asked.
- Good for
- Teams that work with clients or suppliers on the other app, where a request lost between the two costs a client.
- Where it breaks
- Anything your rules keep for a person, like a reply to an upset client, goes to the owner in one message.
How to set up a Slack to Microsoft Teams integration
Short steps in our words. Each one links to the vendor's own page for the screens.
- 1Add Teams calls to Slack
Open the Microsoft Teams Calls page in the Slack Marketplace, click Add to Slack, then Allow, and sign in to your Microsoft account. Anyone with permission to add apps can do this.
- 2Have each person connect their account
In Slack, click Agents & tools in the sidebar, then Apps, and select Microsoft Teams Calls. On the Home tab, click Connect and sign in. Then /teams-calls starts a meeting from any conversation.
- 3Copy messages for the channels that need it
In Zapier, start with Microsoft Teams' New Channel Message for the channel your client uses, then add Slack's Send Channel Message. Build a second zap for the other direction only if you need it.
- 4If you post from Power Automate, check the limits
Use the Post message (V2) action, not the older one Microsoft marks as deprecated. Keep posts under 4,000 characters.
- 5Moving to Teams for good? Export first
Export your Slack workspace, upload the file to Azure Blob Storage and give its address to the migration tool in the Microsoft 365 admin center. On Slack's Free and Pro plans, the export covers public channels only.
Where the Slack Microsoft Teams integration stops
Each of these moves one thing across. None of them keeps one conversation going in both apps, and the vendors' own pages say where the gaps are.
Calls move, messages don't. The Teams Calls app starts and joins meetings from Slack. A request typed in a Slack thread still has to be copied into Teams by someone, and the answer copied back.
Copies are one way, and new messages only. A zap fires when a new message is posted. An edit, a delete or a reply in a thread is a separate trigger or it is missed, so the copy drifts from the real conversation. Power Automate is narrower still: Microsoft's Slack connector lists one trigger, When a file is created, so with that connector a new Slack message can't start a flow.
A move leaves things behind. Microsoft's migration tool skips direct messages, group chats, workflows, app integrations, Slack Connect channels and archived channels. If people keep talking in Slack during the move, later passes add only new messages, and new replies to old messages don't come across. On Slack's Free and Pro plans, the export itself covers public channels only.
And nobody owns the request in the middle. When a client asks for something in Teams and your team works in Slack, someone has to see it, post it, chase it and close the loop with the client. No connector checks that the reply ever went back.
The agents that do it
Each agent does one job from start to finish, in your own Slack and Microsoft Teams.
Ask once in Slack. Someone owns it.
- Takes requests posted in your Slack channelas they come
- Turns each one into a task with an ownerright away
- Follows up until it's doneevery day
Staff ask once. Someone owns it.
- Takes requests posted in your Teams channelas they come
- Logs them and sends each to the right personright away
- Follows up until it's doneevery day
Nothing said in a meeting gets lost.
- Reads the meeting recapafter each meeting
- Posts who owes what, and by whenwithin the hour
- Checks each item got doneevery day
Questions
Is my customers' information safe?
Yes. Agents work in your own Slack and Microsoft Teams and see only what their job needs. Customer details never go into public AI. Agents connect to AI through business-grade connections audited under SOC 2.
Can Slack and Microsoft Teams talk to each other?
In parts. Slack's Microsoft Teams Calls app starts and joins Teams meetings from Slack. Zapier can copy new channel messages from one app to the other. Neither keeps a whole conversation in step both ways.
Can I join a Microsoft Teams meeting from Slack?
Yes. Add the Microsoft Teams Calls app from the Slack Marketplace and connect your Microsoft account. Then type /teams-calls in a conversation, and everyone in it sees a Join button that opens Teams.
Can I move my Slack messages to Microsoft Teams?
Yes, channel messages. Microsoft's Slack to Teams migration tool moves channels, threads, reactions, files and members from a Slack export. It doesn't move direct messages, group chats or workflows.
What does it cost?
You get the price on the call, along with the hours it saves your team.