How to block third party models in Microsoft 365 Copilot?

Blocking or allowing third‑party AI models in Microsoft 365 Copilot is controlled at the tenant level through the “AI providers operating as Microsoft subprocessors” / Anthropic and related settings. The same pattern applies to other external model providers when exposed as subprocessors.

To block third‑party models for Microsoft 365 Copilot:

1. Open the Microsoft 365 admin center as a Global admin.
2. Go to the Copilot / AI provider settings (AI providers operating as Microsoft subprocessors).
3. Turn off the subprocessor/provider you want to block (for example, disable Anthropic as a sub‑processor if Anthropic models should not be used).
   • When Anthropic is disabled, features and agents that rely on Anthropic models (such as Word, Excel, and PowerPoint Agents and other Anthropic‑backed reasoning scenarios) are no longer available to users.
4. Save the changes and allow time for propagation. When disabled, users will no longer see or be able to use Copilot features that depend on those external models.

Key behaviors from the documented settings:

• Anthropic as a sub‑processor: Controls whether Anthropic models (such as Claude) can be used by Microsoft 365 Copilot at all. Disabling this setting blocks those third‑party models tenant‑wide.
• Copilot in Microsoft 365 apps with Anthropic models: Controls whether Anthropic models can be used inside Word, Excel, and PowerPoint. Disabling this prevents Copilot in these apps from selecting Anthropic models for document creation, analysis, and similar tasks.
• Word, Excel, and PowerPoint Agents: These agents “exclusively use Anthropic's AI models.” If Anthropic is blocked as a subprocessor, these agents are automatically hidden and unusable in the Copilot app and in the Tools/Agents UI.

To block all third‑party models, ensure that all external AI providers configured as subprocessors (for example Anthropic) are disabled in the admin center. Copilot will then operate only with Microsoft’s own models within the Microsoft 365 compliance boundary.

If a specific image model (such as Flux.2 Flex) is surfaced only through a particular Copilot feature or agent that is backed by a third‑party provider, disabling that provider (or the corresponding app/agent) at the tenant level is the supported way to prevent its use.

References:

• Optimize Microsoft 365 Copilot configuration settings
• Get started with Word, Excel, and PowerPoint Agents in Microsoft 365 Copilot
• Data, Privacy, and Security for Microsoft 365 Copilot