The
fourth season of the
American television comedy series
How I Met Your Mother premiered on September 22, 2008 and concluded on May 18, 2009. It consisted of 24 episodes, each running approximately 22 minutes in length.
CBS broadcast the fourth season on Monday nights at 8:30 pm in the United States. The complete fourth season was released on Region 1 DVD on September 29, 2009. In the United Kingdom it aired on E4.