Planning a Google Workspace to Microsoft 365 Migration? What Should You Consider?

The safest approach is to treat this as four stages: inventory, pilot, cutover, and validation.
Before choosing a migration tool, confirm exactly what must be moved. Inventory user mailboxes, aliases, Google Groups, shared calendars, delegated access, contacts, room resources, My Drive, Shared Drives, retention requirements, and applications that send mail through Google. Create the matching Microsoft 365 accounts, assign licences, and verify that every Google address maps to the correct Microsoft 365 user.
Next, run a pilot with a small but varied group. Include a large mailbox, a user with delegated access, shared calendars, recurring meetings, mobile devices, and Google Drive content. Check Gmail labels, calendar permissions, contacts, Google Groups, and links to Google files carefully, because these features do not always have a direct Microsoft 365 equivalent. Compare item counts and permissions after the pilot, then adjust the migration plan before moving everyone else.
For the final cutover, lower DNS TTL values in advance and prepare the Microsoft 365 MX, Autodiscover, SPF, DKIM, and DMARC records. Complete one final incremental sync, change mail flow, and confirm that new messages arrive in Microsoft 365 before directing all users to the new service.
After migration, keep Google Workspace available for a short validation period. Check mailbox totals, calendars, permissions, shared data, mail flow, MFA, mobile access, and line-of-business applications before cancelling Google licences. A rollback plan and clear user instructions are just as important as the migration tool itself.

You are planning more than a mailbox move: user mapping, calendars, contacts, coexistence, Drive content, and DNS cutover need separate validation. Inventory users, aliases, groups, shared mailboxes, delegated access, rooms, shared calendars, Drive ownership, and retention requirements. Verify the domain in Microsoft 365, assign licenses, provision every target user, and create the two routing subdomains required for staged coexistence. Use the Exchange admin center’s automated Google Workspace migration in a small pilot batch; it moves mail, rules, calendars, and contacts. Validate counts and representative items before expanding. Document limitations early: shared calendars, event colors, room bookings, Gmail labels, some contact fields, and oversized messages do not migrate identically. Move personal Drives to OneDrive and shared Drives to SharePoint or Teams with Migration Manager. Before cutover, lower DNS TTLs, freeze account changes, complete delta synchronization, switch mail records, and test internal and external delivery. Keep Google read-only until owners sign off.