[6] In addition to many local theatre performances, Olsen trained in improv with ComedySportz Quad Cities and later joined the cast.

The series lasted for a year before he made his transition onto the big screen when he played Ben Affleck's gunner in Pearl Harbor, that was quickly followed by a leading role as Austin "The Cocky Blond Guy" in the teen send up feature film Not Another Teen Movie.

He claimed three highly contrasting roles in 2006 and 2007 with the release of Beerfest, License to Wed and Zach Braff's The Last Kiss.

In 2009, he appeared in several episodes of the first season of the Community sitcom, as Vaughn, a usually shirtless, neo-hippie student, musician, and athlete.

[8] Olsen portrayed Detective Marty Deeks on the CBS show NCIS: Los Angeles.

[17][18][19][20] Olsen and Wright were featured in a 2015 episode of the HGTV series House Hunters buying a vacation home near Jackson Hole.

[21] Olsen works with the charity Hats Off for Cancer as an Honorary Board Member and Spokesperson, featured on their Public Service Announcement video.