The fourth season of the American television series Bones premiered on September 3, 2008, with a two-hour episode and concluded on May 14, 2009, on Fox. The show changed time slots again, airing on Wednesdays at 8:00 pm ET before moving to Thursdays at 8:00 pm ET in 2009. The season consisted of 26 episodes and averaged 10.8 million viewers.