"U Know What's Up" is a 1999 hit song by singer-songwriter-producer Donell Jones' second studio album, Where I Wanna Be. The song features Lisa Lopes of TLC. It reached number one on the Billboard Hot R&B/Hip-Hop Singles & Tracks chart on November 13, 1999, and stayed at number one for eight consecutive weeks. It peaked at number seven on the Billboard Hot 100, remaining there for two consecutive weeks. The song was even more successful in the United Kingdom, where it debuted and peaked at number two on the UK Singles Chart in January 2000. The song was produced by Edward "Eddie F" Ferrell and Darren Lighty for Untouchables Entertainment. It is Jones's biggest hit to date. The song was co-written by Anthony Hamilton.