Microsoft 365 Copilot adds xAI Grok models in limited Frontier preview

On September 14, 2026, Microsoft announced that it is adding Grok models from SpaceX-owned xAI to Microsoft 365 Copilot, giving Word, Excel, and PowerPoint users a third model option alongside OpenAI and Anthropic Claude. The feature is being rolled out as a limited preview through the Microsoft Frontier program, with Frontier customers in the European Union, the European Free Trade Association, and the United Kingdom initially excluded. Microsoft did not specify which Grok model powers the preview; xAI's current flagship is Grok 4.6, released in August. Grok responses inside Copilot will be subject to Microsoft system prompts and enterprise guardrails, keeping the output professional rather than carrying Grok's signature snark from X. Because some customer data may be processed by xAI when Grok is invoked, Microsoft added SpaceX AI to its Online Services Subprocessor list and requires enterprise admins to explicitly enable Grok before employees can use it, while preserving admin visibility and control over data flowing to xAI. The move extends Microsoft's multi-model strategy for Microsoft 365 Copilot, following earlier integrations of Anthropic Claude into Researcher and Copilot Studio as the company reduces its single-vendor dependency on OpenAI. Microsoft said third-party models undergo testing, safety validation, and a Responsible AI review before being added to Copilot, and it remains to be seen whether Chinese vendors such as DeepSeek, Moonshot, and Qwen will be added next.