However, these statements involve risks and uncertainties, including those detailed in our earnings release, our annual report on Form 10-K, as amended, and our other filings with the SEC. Reconciliations of GAAP to non-GAAP measures and certain additional information are also included in our investor presentation and our earnings release. Turning to the agenda, Tom Stanton, Adtran Holdings' CEO and Chairman of the Board, will provide key highlights for the fourth quarter and full year 2025. Earnings came in above expectations, with all three business categories achieving sequential and year-over-year growth.
In the fourth quarter, Adtran generated revenue of $291.6 million, reflecting a strong year-over-year growth of 20% and sequential growth of over 4%. This marks the sixth consecutive quarter of sequential growth and the fifth consecutive quarter of year-over-year improvement, reinforcing the strength of our company and our key markets. business led to quarterly growth, with revenue up 31% year-over-year and 14% sequentially. revenue grew 12% year-over-year and declined 3% sequentially, as expected, and consistent with recent ordering patterns among some of our larger European customers.
Optical networking solutions grew 33% year-over-year, driven by strong sales to cloud providers and enterprise customers. This increase also drove the contribution of enterprise and cloud providers to 25% of our revenue in Q4 and 21% for the full year of 2025. Access and aggregation revenue grew 9% year-over-year and 6% sequentially, supported by continued fiber access investment across the U.S. Subscriber Solutions revenue grew 17% year-over-year and 3% sequentially, driven by demand for our residential fiber CPE as customers continue to connect more subscribers.