Shepard was born in Milford, Michigan, and attended Muir Junior High and Walled Lake Central High School, before enrolling in The Groundlings school. He later received a degree in anthropology at UCLA.
Shepard was an actor on Punk'd with Ashton Kutcher. In 2006, Shepard appeared opposite Dane Cook and Jessica Simpson in the comedy Employee of the Month. During the same time, Shepard began appearing in more films and landed his first main character role in Let's Go to Prison, alongside Will Arnett. He also had a major role in Baby Mama. Shepard wrote the script for the Paramount venture Get 'Em Wet, in which he again appeared with Arnett. He was also in the 2010 movie When in Rome. He is now one of the main characters in the NBC show Parenthood, playing Crosby Braverman.
Shepard donates much of his time to the Hollenbeck Youth Center, an after-school program that provides opportunity to at-risk inner-city youth. He has served as their official Master of Ceremonies, along with his friend Tom Arnold, for the Inner-City Games and Hollenbeck Youth Center's Miracle on 1st Street Toy Giveaway Program in East Los Angeles.
- Hairshirt (1998) as Vomiter at Party (as Dax Sheppard)
- Punk'd (TV Series) (2003) as Ashton Kutcher's minion (field agent)
- Cheaper by the Dozen (2003) as Camera Crew Member
- Without a Paddle (2004) as Tom Marshall
- Sledge: The Untold Story (2005) as SFX Coordinator
- Zathura (2005) as older Walter
- My Name is Earl (TV series) (2005)
- Robot Chicken (2009) Blitzen / Pickles / Ironhide / Human Torch (2 episodes)
- Employee of the Month (2006) as Vince Downey
- Idiocracy (2006) as Frito Pendejo
- Let's Go to Prison (2006) as John Lyshitski
- King of the Hill (TV series) (2006)
- The Comebacks (2007) as the hometown Sheriff
- Knocked Up (2007) as Himself (uncredited)
- Baby Mama (2008) as Carl
- Smother (2008) as Noah Cooper
- Confessions of an Action Star (2008) as Bucky
- Boobies in Space (2008) as Joey the Plumber in Space
- Old Dogs (2009) as Gary (uncredited)
- Parenthood (TV series) (2010) as Crosby Braverman
- When in Rome (2010) as Gale
-  Starpulse.com
- Adam Carolla CarCast, August 15, 2009
- "Exclusive: Kristen Bell Is Engaged To Dax Shepard!". US Magazine. 2010-01-31. Retrieved 2010-02-01.
- http://www.myboxingfans.com/2008/12/hollenbeck-gym-hosts-toy-giveaway/ http://www.contactmusic.com/photos.nsf/main/tom_arnold_5068275
- "Governor Schwarzenegger website" http://gov.ca.gov/speech/8294/