GAAP revenue was a record $318 million, up 5% year-over-year, and adjusted operating income was $118 million, a margin of 37%. During the quarter, we accelerated up-market growth, improved net revenue retention for the fifth straight quarter, delivered another quarter of strong profitability, and are again raising our financial guidance for the year. Our Operations Suite again grew more than 20% year-over-year as our proprietary data asset continues to prove mission-critical to any AI-driven initiative that touches go-to-market. With our Salesforce partnership, ZoomInfo Revenue Agent is now bringing the industry's most comprehensive B2B data and agents directly into AgentForce.
Their CMO called it a no-brainer to improve sales pipeline generation, identify active buying signals, reduce wasted time on unproductive leads, and connect with the right decision-makers. As we innovate for our customers, we continue to be focused capital allocators for our shareholders. In the quarter, we delivered a nearly 300 basis points sequential improvement in margins and are raising our growth expectations for the year. We remain confident in our ability to sustainably deliver revenue growth and expanding margins.
We are building stickier user engagement and customer relationships, and we have improved net revenue retention for the fifth straight quarter. Q3 GAAP revenue was $318 million, up 5% year-over-year, and adjusted operating income was $118 million, a margin of 37% above the guidance ranges we provided. This continued focus drove a two-point acceleration up-market with 6% up-market ACV growth, coupled with a sequential improvement down-market, which declined 10% year-over-year as compared to 11% in the prior quarter. Net revenue retention improved to 90% in the quarter, up 5 percentage points in a year, and the highest level of NRR we have seen since Q2 2023.