He attended Roman Catholic schools.
O'Donnell began modeling at the age of thirteen and was featured in several commercials.O'Donnell was discovered when he was cast in a McDonald's commercial, in which he served Michael Jordan. His first television role was an appearance on the series Jack and Mike in 1986. At the age of 17, he was offered a chance to audition for a part in the movie Men Don't Leave, with Jessica Lange, and he won the role. In the early 1990s, O'Donnell was a featured player in many successful movie
Filmography:
1994 Blue Sky Glenn Johnson
1995 Circle of Friends Jack Foley
Mad Love Matt Leland
Batman Forever Robin/Richard "Dick" Grayson
1996 The Chamber Adam Hall
In Love and War Ernest 'Ernie' Hemingway
1997 Batman & Robin Robin/Richard "Dick" Grayson Nominated – Razzie Award for Worst Supporting Actor
Nominated – Razzie Award for Worst Screen Couple (with George Clooney)
1999 Cookie's Fortune Jason Brown
The Bachelor Jimmie Shannon
2000 Vertical Limit Peter Garrett
2002 29 Palms The Hitman
2003 The Practice Brad Stanfield TV series – 4 episodes
2004 Kinsey Wardell Pomeroy
Two And A Half Men Jill/Bill TV series – 1 episode
2005 The Sisters David Turzin
Head Cases Jason Payne TV series – 2 episodes
2007 Grey's Anatomy Dr. Finn "McVet" Dandridge TV series – 9 episodes
The Company Jack McAuliffe TV miniseries
2008 Kit Kittredge: An American Girl Jack Kittredge
Max Payne Jason Colvin