Jason Jordan Segel was born on January 18, 1980 in Los Angeles, California. In high school Jason played basketball and was on the team who won state in California. He also played the piano. In 1998 Jason appeared in the films Can't Hardly Wait, SLC Punk!, and Dead Man on Campus. The following year Jason appeared in New Jersey Turnpikes and also in the series Freaks and Geeks. Additional film credits include Certainly Not a Fairytale, The Good Humor Man, and Lollilove.

On television, Jason has appeared with recurring roles on CSI: Crime Scene Investigation and Undeclared. He also made a guest appearance on Alias. In 2005 Jason landed the role of Marshall on CBS's How I Met Your Mother.