OpenAI accounts for over 50% of Microsoft's AI revenue, disclosed in rare corporate transparency; raises questions about Microsoft's strategic dependence on single vendor.
Microsoft generated $24.1 billion in revenue from OpenAI during fiscal year 2026, according to the company's Form 10-K filing submitted to the U.S. Securities and Exchange Commission on July 29. This marks the first time Microsoft has publicly disclosed the full scale of commercial revenue derived from OpenAI.
The disclosure did not appear in Microsoft's fourth-quarter earnings report released the same day, but rather in the detailed regulatory filing. When releasing its quarterly results, Microsoft did not provide an updated figure for total AI-related revenue.
To date, Microsoft has disclosed the total scale of its AI business only twice: it stated that the business was on track to achieve an annualized run rate of $13 billion for the quarter ended December 2024, and CEO Satya Nadella indicated that AI-related annualized revenue was approaching over $37 billion for the quarter ended March 2026.
Based on institutional estimates assuming Microsoft's AI business sustained the 123% year-over-year growth rate disclosed for the March quarter, the company's AI business reached approximately $34 billion by the end of fiscal year 2026. According to this projection, OpenAI's contribution of $24.1 billion would account for more than half—and potentially as much as around 70%—of Microsoft's actual AI sales in fiscal year 2026. When compared to Microsoft's total revenue, however, OpenAI's share appears considerably smaller—less than 10%.
Microsoft's total AI-related revenue encompasses all income generated from cutting-edge large-model clients as well as revenue from sales of AI products to a broad range of customers. Under their cooperation agreement, OpenAI pays Microsoft for Azure cloud computing and inference compute usage, development costs, and a percentage of its revenue as a sharing payment.
Despite Microsoft's efforts to reduce its reliance on OpenAI—including investments in Anthropic and the development of its own AI models—OpenAI remains the primary driver of Microsoft's projected revenue growth. During its fourth-quarter earnings call, Microsoft noted that approximately $51 billion in sequential commercial bookings (RPO) came from customers outside AI startups. However, across the full fiscal year, media reports indicated that OpenAI still accounted for the majority of annual booking growth.
Jackson Ader, an analyst at KeyBanc Capital Markets, raised an unresolved question regarding the $24.1 billion figure: how much stems from revenue-sharing agreements with OpenAI versus from cloud computing or other Microsoft services. "If this revenue primarily arises from services Microsoft provides to OpenAI rather than from investment-like returns tied to its shareholder status, I would view it more favorably," Ader noted.
Microsoft is OpenAI's largest external shareholder, holding approximately 27% of diluted equity. The company is entitled only to economic benefits and holds no voting rights over operations. Investment gains or losses related to this equity stake are not included in Microsoft's reported AI revenue from OpenAI, though the commercial revenue-sharing agreement is linked to its shareholder status.
Prior to this disclosure, Microsoft had never explicitly revealed the full amount of revenue it derived from OpenAI. Olga Usvyatsky, founder of data analytics firm Nonlinear Analytics and an accounting researcher, speculated that this disclosure may be related to OpenAI's preparation for an initial public offering.