Bierko was born in Rye Brook, New York, the son of Pat (Distillator) and Rex Bierko, who ran a local community theatre. Bierko’s mother was a Jewish-born convert to Roman Catholicism. Bierko has said he is “very connected” to his Jewish heritage. His surname is Polish. He attended Blind Brook High School and then went on to Boston University intending to study broadcast journalism at the School of Public Communications but graduated from Northwestern University in 1986 with a BS in theater arts from the School of Speech.

Bierko got his break in 1990 when he was cast opposite Valerie Bertinelli and Matthew Perry in the CBS sitcom Sydney; however, the production lasted just 13 episodes. He went on to make steady appearances in various television shows including Amen, The Powers That Be, Wings and Ally McBeal. Bierko may be best known for his role as Timothy in the 1996 action film The Long Kiss Goodnight (a role he credits as the beginning of his penchant for “darker” roles), as Max Baer in the film Cinderella Man, as Tom Ryan in Scary Movie 4 (spoofing Tom Cruise throughout the film) and on the Broadway stage as Harold Hill in The Music Man, or as the lead in The Thirteenth Floor. He was also the original choice for the character of Chandler Bing on the sitcom Friends but turned it down. He had a small role as a jazz musician love interest for Carrie Bradshaw (Sarah Jessica Parker) in the fourth season of Sex and the City. He had another small role as attorney Jeffrey Coho during the third season of the ABC television series Boston Legal and as a lead in the short-lived Unhitched. He was also cast as Dave Lister in the pilot for the American TV version of Red Dwarf, which was not picked up as a series. He appeared in 2001’s Kate & Leopold in an uncredited role, and in TV’s Law & Order: Special Victims Unit as Andy Eckerson, a United States Deputy Marshal who is working with the SVU (and ex-flame Det. Olivia Benson) to recapture an escaped convict.

Bierko was slated to appear on Broadway in the Manhattan Theatre Club production of To Be or Not to Be but withdrew from the production August 29, 2008, for unspecified reasons. He starred as Sky Masterson in the Broadway revival of Guys and Dolls which began performances at the Nederlander Theatre on February 5, 2009, and officially opened on March 1, 2009. The production closed on June 14, 2009 after 113 performances. He performed the role of Peter in the 2011 New York Philharmonic production of Stephen Sondheim’s Company with Neil Patrick Harris, Patti Lupone and Stephen Colbert.