He got his start in the third season of Murder One in 1996, playing Aaron Mosley. After that series' cancellation, he guest starred on The Practice, Snoops, The Division and Once and Again. He made a guest appearance on JAG in its final season as FBI Agent Rod Benton. From 2002-03, Woodside starred in 14 episodes of Buffy the Vampire Slayer's final season, as Principal Robin Wood, Buffy's boss and son of a Slayer. He followed this up in the following television season, playing the pragmatic Wayne Palmer, the Chief of Staff and brother to President David Palmer during the third season of the hit Fox series 24. In the fifth season of the series, he returned to reprise the role as a guest star in episodes 1–2 and 14–18. Woodside returned as a series regular for the sixth season as the President of the United States.