Unified Company Calendar for Mixed Microsoft 365 and Non-365 Users – 2025

Seeking a Shared Calendar Solution for Mixed Microsoft 365 and Non-365 Users

I’m working on a solution to create a shared company calendar that everyone in our organization can view, while keeping editing permissions limited to a few selected individuals.

The challenge:

Some of our team members do not use Microsoft 365, and I’d like them to still be able to subscribe to or view the calendar and receive updates.

Ideally, this should work without requiring full Microsoft accounts.

I initially considered using an ICS-based calendar, but it seems Microsoft 365 Group calendars don’t support sharing via ICS links. I also explored creating a Group calendar as suggested in other threads, but ran into issues making it accessible to external users or those without 365 accounts.

For context, I’m a Global Admin, so I have full access to configure settings in the Microsoft 365 Admin Center and Exchange if needed.

We’re a small business, and our main goal is to have a centralized calendar for vacation schedules and company-wide events. It should be simple to access and maintain, with a focus on collaboration and accessibility across the board.

What I’m looking for:

• A calendar that’s viewable by all, including non-M365 users
• Editable only by a few delegated team members
• Compatible with Microsoft 365, but not dependent on it for basic access
• Any tools, workarounds, or best practices that have worked for others in similar hybrid environments