Horovitz began his music career with a rock band the Young and the Useless. In 1982, he joined Beastie Boys. The Beastie Boys changed their sound, after he joined, evolving from a hardcore punk band to a more hip-hop oriented group. The band got famous worldwide and in 2012, the Beastie Boys were inducted into the Rock and Roll Hall of Fame. Horovitz was married to actress Ione Skye in 1992 and married, a musician and feminist activist,Kathleen Hanna in 2006. He wore a medical alert bracelet after having a Tonic–clonic seizure in 2003.He also remixes numerous tracks for other artists under the alias 41 Small Stars and plays bass in The Tender Moments, the backing band of New York-based cabaret performer Bridget Everett. He acted in several motion pictures and television shows. Some of his roles include Tim 'Chino' Doolan in Lost Angels (1989), Repulski in Godspeed (2007), and Fletcher in While We're Young (2014).