Grok models are now selectable inside Microsoft Copilot, confirmed September 12 — the xAI/Microsoft partnership moving from press release to product. Users get a non-Microsoft model choice inside the same Copilot surface.

Separately, SpaceXAI was added as a Copilot subprocessor with an opt-in admin setting that enables Grok inside Word, Excel, and PowerPoint for Frontier customers (excluding EU/EFTA/UK and government tenants), effective September 18. This is the real distribution play: Grok inside Office documents.

Watch the opt-in numbers — model choice inside enterprise Copilot is a genuine shift in how frontier models reach office workers.