How to Connect Multiple Google Calendars to Gemini
Gemini holds one Google account at a time, so a second account’s calendar is out of reach until Carly holds it for you. Connect each Google account to Carly, add Carly to Gemini as a custom app, and one chat covers a personal calendar, a Workspace calendar, and everything shared into either. Carly holds your Outlook calendars and every mailbox on both sides in the same place, so this setup covers the rest of what you own.
What one chat can do afterwards
- Read every connected calendar in a single question.
- Catch a clash between a personal and a work account.
- Book on the account that actually owns the meeting.
- Invite attendees, which Gemini’s own calendar connection will not do.
- Update the location or description of an existing event.
- Act the moment an invite lands, rather than at the next scheduled run.
Nothing is merged. Each Google account stays separately authorized and individually addressable, so every instruction can name one.
1. Sort your calendars
| Calendar | Owner | Reachable in one Gemini chat |
|---|---|---|
| Your primary calendar | Your signed-in account | Yes |
| A secondary calendar you created | Same account | Read and booked, but no attendees |
| A team calendar shared to you | Same account | Read only, at the permission granted |
| A calendar in your other Google account | Another account | Only through Carly |
| A second employer’s Workspace calendar | Another account | Only through Carly |
2. Connect each Google account to Carly
- Sign in at carlyassistant.com.
- Open carlyassistant.com/integrations.
- Find Google Calendar and click Connect.
- Authorize the first Google account.
- Repeat for every additional account, personal and Workspace alike, choosing Use another account when Google preselects the first login.
- Verify each account after authorization.
If a Workspace account requires administrator review, ask that Workspace administrator to approve the connection, then finish authorizing. Each Workspace approves independently. Connected calendars are unlimited on the scheduling side, so a third Google account does not change what you pay.
3. Add Carly as a custom app in Gemini
- Go to gemini.google.com on a computer.
- Open Settings & help → Connected Apps.
- Under Custom apps for Spark, click Add a custom app.
- Enter
https://carlyassistant.com/mcp/. - If prompted, open Show more under Advanced features to enter credentials.
- Click Next and follow the on-screen instructions.
You work with Carly directly from step 2. The calendars are connected and usable the moment you authorize them; adding Carly to Gemini is what puts them inside a Gemini chat, and it is optional. Most readers stop here.
Google gates that last step. Custom apps need a personal Google Account, because the feature “isn’t available if you sign in with a work or school Google Account,” plus being 18 or over and in the US, with Keep Activity switched on. None of that touches the accounts you connected to Carly, and a work Google identity is exactly the case Carly covers.
Google notes that it does not control or secure third-party MCP servers, and asks you to understand what a server does before connecting it. Carly’s actions are the calendar and mail operations you authorized per account, and you can disconnect any of them at carlyassistant.com/integrations at any time.
4. Test read-only first
One account per prompt until routing is reliable:
On my work account, list every meeting on the Client Delivery calendar next week. Read only, change nothing.
On my personal account, show anything on the Family calendar that overlaps working hours next week.
Then the cross-account question that was not possible before:
Show one combined agenda for next Tuesday across both Google accounts, marking which account each event belongs to and flagging any two that overlap.
5. Reuse this routing prompt
Treat my Workspace address as Work and my Gmail address as Personal. Name the target account and the target calendar before creating, moving or cancelling anything. Never write to a calendar I have not named.
Then name the target per action:
Book the Databricks review on the Work account’s Client Delivery calendar for Thursday at 3pm, invite Priya and Tom, and block the travel either side on my Personal calendar.
Where Gemini’s own calendar connection stops
Calendar reaches Gemini through the Google Workspace app in Connected Apps, not a standalone Google Calendar connector. That single app covers Gmail, Calendar, Docs, Drive, Keep and Tasks together, and Google’s Gemini Apps help documentation confirms you can create and manage events on your secondary and shared calendars, not only the main one. What it will not do, on any calendar, is invite attendees or change an existing event’s location or description.
Three things bound it, and each is the reason a reader ends up here:
- The account boundary. Connected Apps is configured per identity, and Google’s instruction is to sign in to the same account you use with Google Workspace. Account switching moves between accounts rather than holding two, so nothing produces a single answer spanning a personal Gmail calendar and a Workspace calendar at Ford. Personal Intelligence, where these settings now live, is a personal-account feature and is not available on work, school or supervised accounts, so the two halves of the problem do not even share a settings screen.
- The write set. Google lists two actions Gemini cannot perform in your calendar: adding or inviting people to events, and adding or updating the location or description of an existing event. An event you cannot add attendees to is a meeting you still finish by hand. Writes also land on your default calendar unless you name a different one, quietly, with no error.
- The automation ceiling. There is no calendar trigger. Scheduled actions run on the clock, cap at ten active at a time, and carry Google’s own warning that their responses are prepared in advance, so fast-moving data will not be current. Nothing happens because an invite arrived.
Sharing a second account’s calendar into the first is the one native bridge, and it is a partial one. The permission level you grant is the ceiling, See only free/busy hides event details entirely, a Workspace administrator decides whether you can share outside the organization at all, and everything else in that second account, the mailbox and the files, stays behind.
Native Gemini versus Carly
| Need | Gemini | Carly |
|---|---|---|
| Book on a second Google account’s calendar | No | Yes |
| Invite attendees to an event you create | No | Yes |
| Invite attendees to an event | No | Yes |
| Update an existing event’s location or description | No | Yes |
| Hold two Google accounts at once | No | Yes |
| Act when an invite arrives | No | Yes |
Carly holds several Google identities at once, writes to the calendar you name, and adds attendees. It fires on the event rather than on the clock: the invite arrives, the clash against your other account is caught, and the alternative time goes out before you have opened the tab. Free Zapier-style workflows; AI agents from $35/month. Connect it at carlyassistant.com/integrations, or start with Google Calendar.
Quick fixes
| Problem | Fix |
|---|---|
| Add a custom app is missing in Gemini | Confirm a personal Google Account, Spark access, US location, and that Keep Activity is on |
| Gemini says it cannot reach Calendar | Turn on Keep Activity and Gmail’s smart features setting, then re-check Connected Apps |
| The event landed on the wrong calendar | Name the calendar in the prompt; writes default to your primary |
| A shared calendar shows busy blocks only | You were granted See only free/busy; ask for See all event details |
| Gemini will not add the guests | Documented limit; route the booking through Carly instead |
| Your other account’s calendar is invisible | Connect that account at carlyassistant.com/integrations |
Frequently asked questions
Can Gemini see calendars from two Google accounts at once?
Not on its own. Connected Apps is set per identity and Google’s instruction is to sign in to the same account you use with Workspace. Connecting each account to Carly and adding Carly as a custom app keeps every calendar reachable from one chat.
Can Gemini access more than one Google Calendar?
Within one signed-in account it reads and books them, with no separate connection step per calendar. What it will not do on any of them is invite attendees or update an existing event’s location or description, and it cannot reach a calendar in your second Google account at all. Carly does all three.
Why did Gemini put my event on the wrong calendar?
Because you did not name one. Google states that Gemini creates events on your default calendar unless you specify a different calendar, so the target has to be in the prompt every time.
Can Gemini invite people to a meeting it creates?
No. Google lists adding or inviting people to events as an action Gemini cannot perform for you, along with adding or updating the location or description of an existing event. Carly does both.
Does Gemini do anything when an invite arrives?
No. There is no calendar trigger. Scheduled actions run on a timer, are capped at ten active at once, and Google warns their responses are prepared in advance, so nothing reacts to an invite landing.
Related: Multiple Gmail accounts in Gemini · Multiple Google Calendars in Claude · Best AI assistants for Google Calendar · Google Calendar integration
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