Security Policy Errors

How to Add Guest Users to Custom Roles in Microsoft 365 Defender

Natalie Taylor Oct 10, 2026 869 views

Question details

The user needs to know how to add guest users to custom roles in the Microsoft 365 Defender portal, particularly when those guest users are missing from user search results.

How to Add Guest Users to Custom Roles in Microsoft 365 Defender

Product: Microsoft 365 Defender
Device & OS: not provided
Scenario: Assigning security permissions and custom roles to external guest users within a Microsoft 365 environment.
Observed behavior: Guest users occasionally do not appear in the user search results when administrators attempt to add them to custom roles in the Microsoft 365 Defender portal.

Before you start

Ensure you have Global Administrator or Security Administrator privileges in the Microsoft 365 admin center before attempting to manage custom roles.

Solution 1Recommended

Verify Tenant Configuration and Open a Support Request

Guest users can be added through the portal in supported configurations. If they are missing, you must verify your settings or contact Microsoft Support to investigate your tenant.

Testing confirms that guest users can be successfully added to custom roles through the Microsoft 365 Defender portal. However, depending on your specific tenant configuration or propagation delays, these accounts may temporarily not appear in the search directory.

Confirm Guest Account Status

Navigate to Azure Active Directory (Entra ID) and confirm that the guest user has fully accepted your organization's invitation and is listed as an active guest user.

Search in the Defender Portal

Log in to the Microsoft 365 Defender portal, navigate to the Roles section, and attempt to search for the guest user's exact email address rather than just their display name.

Open a Service Request

If the guest user is still unavailable, go to the Microsoft 365 admin center. Navigate to the 'Support' tab and select 'New service request'.

Request Diagnostic Investigation

Detail your issue in the service request, specifically mentioning that guest accounts are missing from the Defender portal role search. Microsoft Support will investigate your tenant configuration and collect necessary diagnostic logs to resolve the issue.

Verify Tenant Configuration and Open a Support Request

Support Investigation: Because backend tenant configurations can restrict guest visibility in specific administrative portals, Microsoft Support has the proprietary tools required to collect logs and correct these synchronization issues.

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Frequently Asked Questions

Can guest users be assigned custom roles in Microsoft 365 Defender?

Yes, guest users can be assigned to custom roles within the Microsoft 365 Defender portal, provided that the Microsoft 365 tenant configuration supports it and the guest is properly added to the directory.

Why are my guest users not showing up in the Microsoft 365 Defender user search?

This usually occurs due to backend tenant configuration restrictions, directory synchronization delays, or insufficient administrative privileges. Searching by the exact email address can sometimes bypass display name search limitations.

What should I do if a guest account remains invisible in the role assignment menu?

You should navigate to the Microsoft 365 admin center and open a service request. Microsoft Support will need to review your tenant configuration and collect diagnostic logs to fix the missing guest search results.

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