Sync Google Calendar to Outlook with Power Automate or Make

A dependable calendar mirror needs more than “when Google creates an event, create one in Outlook”. Store the Google event ID and returned Outlook event ID, then use that mapping for updates and deletes.

This guide describes one-way Google-to-Outlook mirroring. It is not conflict-free two-way sync.

Fact-checked against current Microsoft, Google Calendar connector and Make documentation on 24 August 2026.

Choose the automation platform

Power Automate

Microsoft's Google Calendar connector documents triggers for events added, updated or deleted. The Office 365 Outlook connector provides Create event (V4); Microsoft marks older Create event versions deprecated.

Use this route when Power Automate is approved in your environment and both connectors meet your policy and licensing requirements.

Make

Make documents Google Calendar and Microsoft 365 Calendar modules that can watch, create, update and delete events. Use it when Make is an approved integration platform and its connections, scopes and operations fit your governance.

The Make URLs in this article retain Collab365's affiliate parameter. No price, quota or saving is claimed.

Create a mapping store

Use SharePoint, Dataverse or another approved store with:

• Google calendar ID
• Google event ID
• Google last-updated value
• Outlook calendar ID
• Outlook event ID
• Last successful operation
• Sync status
• Error summary

Make the Google calendar ID plus event ID unique. This protects against two runs creating two Outlook copies.

Handle creates

1. Trigger when a Google event is added.
2. Check the mapping store for its event ID.
3. If a mapping exists, stop or route to update logic.
4. Convert start and end times explicitly.
5. Create the event in Outlook with Create event (V4) or the corresponding Make module.
6. Save the returned Outlook event ID.

Do not use the event title as an identifier. Titles are not unique and users edit them.

Handle updates

When Google reports an update:

1. find the mapping;
2. retrieve the current source values;
3. update the mapped Outlook event;
4. save the new source last-updated value.

If the mapping is missing, decide whether to create, ignore or send the event for review. Silent creation can duplicate events after somebody deletes a mapping row.

Handle deletes

When Google reports deletion or cancellation:

1. find the mapping;
2. delete or cancel the mapped Outlook event according to your business rule;
3. retain a tombstone record so a retry does not recreate it;
4. record completion.

Test what each connector emits for cancelled events. Do not infer deletion from a missing search result.

Time zones and all-day events

Calendar errors often come from treating a local time as UTC.

• Preserve the source time zone where the connector supplies it.
• Convert explicitly before creating the Outlook event.
• Test daylight-saving transitions.
• Treat all-day events separately because their date boundaries differ from timed events.
• Check whether the Outlook action expects a named time zone as well as date-time values.

Recurring events

Recurring series can expose a series master and individual occurrences differently. Prove create, one-occurrence edit, whole-series edit and cancellation before enabling recurrence mirroring.

If the connectors cannot preserve your recurrence pattern reliably, exclude recurring events and say so in the process documentation.

Prevent loops

Keep the integration one-way. If another flow also copies Outlook events back to Google, add a source marker and stable mapping that both routes respect.

A subject prefix is not a reliable loop guard because users can edit it.

Privacy and permissions

Calendar details can be sensitive. Decide whether the mirror should copy:

• attendees;
• body and conferencing links;
• private-event details;
• location;
• reminders;
• attachments.

Use the least-permission accounts and scopes that meet the need. A personal Google connection owned by one employee is a fragile production dependency.

Sources

• Microsoft Google Calendar connector
• Microsoft Office 365 Outlook connector
• Make Google Calendar documentation
• Make Microsoft 365 Calendar documentation

Review the mapping before switching it on

Bring sample create, update and delete events to the Power Automate Builders Space. The Make signup link and the Space CTA use separate attribution.