Migrating email, calendars and files into Microsoft 365 is well-established territory. Migrating the conversations people actually have at work has been less straightforward — and until now, organisations moving from Slack to Teams have largely relied on third-party tools or partners to bring channel history across.
Microsoft has now released its own option. The Slack to Teams Migration Tool from Microsoft is available immediately to all standard commercial customers worldwide, and runs inside the Microsoft 365 admin center.
What the tool migrates today
The current release covers more than just channel names. According to Microsoft's announcement and the supporting Microsoft Learn documentation, the tool migrates:
- Slack channels, both public and private
- Channel messages, including threaded replies and standard reactions
- Message content such as formatting, links, images, @-mentions and standard emojis
- Channel file attachments
- Canvas and list content, imported into the Teams channel as HTML and JSON file attachments respectively
- Channel membership, including owners and members
Microsoft also highlights that migrated messages appear in Teams as if they had been posted natively, with the original author and creation timestamp preserved. That detail matters for compliance, eDiscovery and the basic question of trust in the migrated record.
The tool is positioned both as a self-service option for customers running their own migration, and as something migration partners can use as part of a wider project.
Cost and prerequisites
The migration tool itself has no licensing cost. Customers do need to provide an Azure Blob Storage subscription and container to temporarily hold their Slack export files while the migration runs. Azure Blob Storage carries its own consumption-based cost, but the storage is only needed for the duration of the migration and can be removed afterwards.
The Microsoft Learn documentation sets out the required permissions: a Microsoft 365 Migration Administrator role (recommended) to run the migration, and a one-time Global Administrator consent to allow the Microsoft 365 Teams Migration app to import data into the tenant. Slack-side, customers generate the export package through the standard Slack workspace administration interface.
What's not in scope yet
Microsoft has been explicit about the gaps in the first release. Coming over the next year:
- Group chats from Slack into Teams
- Direct messages — 1-on-1 chats
- Slack canvas content migrated into Microsoft Loop tabs in Teams (canvases currently come across as HTML attachments, so this is a fidelity upgrade)
- An experience in Teams designed to feel familiar to users coming from Slack
There is no published date for any of these items. Microsoft is openly asking for customer feedback on which additional scenarios to prioritise.
The DM and group-chat gap is the one most worth flagging at the planning stage. Slack stores both as constructs that don't map cleanly onto Teams chat objects, which is part of why they aren't in the first release. For organisations where significant working context lives in DMs or private group chats, that history will either need to stay in a read-only Slack tenant, be exported separately, or wait for the roadmap to catch up.
How this sits alongside third-party options
Several ISV tools have offered Slack-to-Teams migration for years, and they continue to be available. The arrival of a first-party Microsoft tool doesn't displace them — particularly for larger or more complex migrations involving DMs, workflows, app integrations or bots, which are out of scope for Microsoft's current release.
What it does change is the baseline. The native option is free at the tool layer, runs inside the admin center most M365 administrators already use, and is aligned with the same documentation set as the rest of M365 migration. For straightforward channel-content migrations, that's likely to be enough. For everything else, the partner and ISV ecosystem remains relevant.
For the European Microsoft community — where Slack has a meaningful footprint alongside Teams, and where consolidation projects keep landing on consultants' desks — having a supported native path with predictable scope is a useful addition to the toolkit, and a topic the partner conversations at ECS tend to cover in detail.