Report says OpenAI accounts for most of Microsoft’s AI revenue

Microsoft’s AI revenue reportedly depends heavily on OpenAI, with a Bloomberg analysis cited by The Decoder estimating that OpenAI generated $24.1 billion for Microsoft in the fiscal year ending in June.

That figure is described as roughly 70 percent of Microsoft’s total AI business. If accurate, it puts a clear number on a relationship that has shaped the enterprise AI market: Microsoft sells a broad AI stack, but a large share of the revenue still flows through OpenAI-linked demand.

The report helps explain Microsoft’s recent interest in broader model choice. A company known for tightly integrated platforms has been pushing open-weight models and interoperability more visibly, which could reduce strategic dependence on any one lab over time.

The number is still an outside analysis, not a full internal breakdown from Microsoft. But the practical implication is hard to miss. Cloud AI platforms are not only competing on infrastructure; they are also managing concentration risk around the few model providers that drive the most customer spending.