Google Workspace to Microsoft 365: A Migration Playbook
How to move email, files, and identities from Google Workspace to Microsoft 365 without losing data or downtime.
Moving from Google Workspace to Microsoft 365 looks simple until you are staring at thousands of mailboxes, shared drives with tangled permissions, and a domain that has to keep flowing mail the entire time. The migration itself is rarely the hard part. The sequencing is.
Inventory first
Before touching anything, get a true picture: mailbox count and sizes, shared drives and their sharing models, groups and distribution lists, third-party apps using Google SSO, and every place the domain is referenced in DNS. The surprises live here.
Decide on coexistence
For anything but the smallest org, plan for a period where both platforms run side by side. Mail routing, calendar free/busy, and a staged user cutover let you move in waves instead of one risky weekend. Coexistence costs a little complexity and buys you a lot of safety.
Migrate in the right order
- Identity first. Stand up Entra ID, decide on SSO, and provision accounts before data moves.
- Mail, calendar, contacts. Migrate in batches, validating fidelity as you go.
- Files. Drive to OneDrive and SharePoint, preserving folder structure and re-mapping permissions deliberately. Shared Drives map to SharePoint sites, not personal OneDrive.
- Cutover. Flip MX and SSO per wave, with a tested rollback at each step.
Watch the sharp edges
Calendar invites with external guests, shared mailboxes, delegated access, and Google Group behavior rarely map one-to-one. Document the differences and set expectations with users before, not after.
Train and communicate
The technical migration can be flawless and still feel like a failure if people cannot find their mail on Monday. A short guide, a clear timeline, and a staffed support channel during cutover week matter as much as the data move.
Done in waves with coexistence and a rollback at every step, a Workspace to Microsoft 365 migration becomes a series of small, boring cutovers instead of one high-stakes leap. The reverse direction, Microsoft 365 to Google Workspace, follows the same playbook in mirror image.