Berkeley was born in Brooklyn, New York, though he has lived most of his life in New Jersey. Berkeley went to Hampshire College and worked in the theaters at the five college system which Hampshire was a part of, including Smith, Mount Holyoke, Amherst, and the University of Massachusetts. Berkeley worked in the Regional and Repertory Theaters in addition to Off Broadway while living in New York. Despite a classically trained theater background, he was increasingly drawn to the subtleties of film acting. A play written by Reynolds Price called Early Dark had such a cinematic feel to it, that an agent saw the acting potential in Berkeley and encouraged him to make the move out west.
Berkeley began playing minor roles in 1981, with early appearances in M*A*S*H, Cagney & Lacey, Remington Steele, Miami Vice, Moonlighting and The A-Team. Although not becoming a household name, Berkeley's face was increasingly recognizable into the 1990s. His later television guest roles included The X-Files, CSI, ER, 24 and Law & Order.
On the big screen, Berkeley has appeared in North Country, Terminator 2: Judgment Day, Phoenix, "Kickass" A Few Good Men, The Rookie, Candyman, Apollo 13, Leaving Las Vegas, Gattaca, The Rock (uncredited), Air Force One, Sid and Nancy, Spawn, Amistad, Shanghai Noon, Barb Wire and Timecode. Berkeley has the distinction of appearing in both the made-for-TV movie L.A. Takedown in 1989 and its 1995 critically-acclaimed theatrical remake Heat, both directed by Michael Mann. Several of his earlier roles were in films by director Alex Cox. Berkeley often plays the roles of unsympathetic characters. In 2001, Berkeley became a recurring guest star on 24 as George Mason, the head of the Counter Terrorist Unit. His character, initially presumed evil by other characters, was revealed to be one of the good guys and became a main character in season 2, only to meet an untimely but heroic end during that season. He also met his wife and co- star, Sarah Clarke, during his career on 24.
Berkeley appeared as Shakespeare in Tom Stoppard's The 15-Minute Hamlet.
Berkeley has provided voices for animated series such as Aaahh!!! Real Monsters, Teen Titans and Gargoyles. He voices Quentin Beck/Mysterio in The Spectacular Spider-Man
Berkeley portrayed the mysterious John Smith on the CBS drama Jericho. He began portraying the series regular role of Percy on The CW's drama Nikita at the start of the 2010-2011 television season.