--- title: "Introducing GPT-5 in Microsoft 365 Copilot: What’s new and how to get value fast" description: Discover the new capabilities of GPT-5 in Microsoft 365 Copilot, enhancing productivity with smarter reasoning, fewer errors, and improved workflows across your favorite apps. image: https://blog.definity.io/hubfs/Screenshot%202025-10-09%20at%202.16.03%20PM.png --- [![Definity Logo-color 1](https://blog.definity.io/hubfs/Definity%20Logo-color%201.svg)](https://blog.definity.io/) - [What We Do](https://blog.definity.io/blog) - [Who We Are](https://blog.definity.io/blog) - [Our Work](https://blog.definity.io/blog) - [Engagement Model](https://blog.definity.io/blog) - [Resources](https://blog.definity.io/blog) [Contact us](https://497782.hs-sites.com/definity-contact-us) ☰ Blog # Definity Discourse Oct 09, 2025 # Introducing GPT-5 in Microsoft 365 Copilot: What’s new and how to get value fast ![Introducing GPT-5 in Microsoft 365 Copilot: What’s new and how to get value fast](https://blog.definity.io/hubfs/Screenshot%202025-10-09%20at%202.16.03%20PM.png) On August 7, 2025, Microsoft began rolling out GPT-5 to Microsoft 365 Copilot and Copilot Studio. The headline: faster, more reliable reasoning in the apps people use every day - Outlook, Teams, Word, Excel, PowerPoint, plus new options for makers building agents in Copilot Studio. OpenAI’s brief on GPT-5 backs that up. Compared to the prior generation, GPT-5 is designed to reason better with fewer errors, reduce hallucinations, and do more with less thinking time. In evaluations, GPT-5 produced materially fewer factual mistakes than earlier models when web reasoning was needed. **What changes for end users** - **Sharper summaries and drafts in context:** Expect tighter meeting recaps in Teams, clearer email drafts in Outlook, and more precise “write & refine” loops in Word, especially on ambiguous requests where prior models struggled.  - **Better analysis helpers in Excel/Power BI workflows:** GPT-5’s reasoning upgrades mean more reliable explanations of trends and assumptions when you ask “why did this move?” or “what’s driving variance?”, not just the chart, but a defendable narrative. - **Fewer follow-ups to fix basics:** GPT-5 is tuned to make fewer factual slips and require less back-and-forth to land on the right structure or next step.  **What changes for builders (Copilot Studio)** - **Model selection with GPT-5:** Makers can pick GPT-5 for new or existing agents. Microsoft notes it’s rolling through early release rings before broad availability, so timing can differ by tenant/environment.  - **Same governance, better brains: **You still ground agents on your data (Graph, SharePoint, Dataverse, websites/APIs) and keep tenant boundaries, RBAC, audit logs, the model upgrade doesn’t change those controls. (Microsoft’s Copilot model swaps happen behind the scenes; admins choose where GPT-5 is allowed.)    **Why this upgrade matters** - **Reasoning > autocomplete:**  GPT-5 is built to plan steps, check itself, and explain the “why,” which is what knowledge work actually needs.  - **Reliability:**  OpenAI reports 45% fewer factual errors than GPT-4o on real-world web tasks, and even bigger gains in high-effort reasoning. That translates to fewer edits and faster reviews.  - **Everyday impact:** Microsoft’s messaging positions GPT-5 as a work upgrade inside Outlook, Teams, Word, and Excel, rather than a separate chatbot experience.    GPT-5 makes Microsoft 365 Copilot more capable at real work. We recommend that you start by upgrading a couple of high-leverage workflows (email triage, meeting notes, executive briefs, or forecast analysis), measure the gains, and then scale to agents in Copilot Studio. 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