Steven Michael Kazee was born and raised in Ashland, Kentucky. He is an alumnus of Fairview High School and Morehead State University. Kazee moved to New York City in 2002 and received his MFA from the Graduate Acting Program at NYU's Tisch School of the Arts.
In 2006, Kazee played Dumas Shepherd in an episode of the television series Conviction. In 2007, he appeared as Michael Barlow in Medium and Mark Green in Numb3rs.
In 2008, he appeared on NCIS as Michael Locke. In 2009, he played Dominic Humphreys on CSI: Crime Scene Investigation. Kazee had a starring role on the CMT's Working Class (2011), in which he played Nick Garrett.
In 2013 he appeared on Elementary as Jeff Hines and on Drop Dead Diva as Dustin Wycott. In 2015, he played Gus Pfender in a recurring role in season 5 and 6 of Showtime's series Shameless.
On stage, he starred in shows both on- and Off-Broadway and in regional theater. He appeared in the NYSF's As You Like It in June 2005.
In 2006, he appeared as Timmy Cleary in The Subject Was Roses, which played at the Kennedy Center from January 7 to 29.
He appeared in Seascape on Broadway in November 2005 as the Leslie understudy, and as the replacement Sir Lancelot in Spamalot on Broadway, starting on April 4, 2006.
In 2007, he starred as Bill Starbuck in the revival of 110 in the Shade on Broadway, and in 2008, he played Sobinsky in To Be Or Not To Be, which ran from September 16, 2008 through November 16, 2008 at the Samuel J. Friedman Theatre.
Kazee starred as Guy in the stage adaptation of Once, which began previews on Broadway on February 28, 2012 and opened on March 18, 2012 at the Bernard B. Jacobs Theatre. He originated the role Off-Broadway when it opened at the New York Theatre Workshop on December 6, 2011. In March 2012, Playbill interviewed Kazee and, since the show's opening, Kazee has made several TV appearances with the show, including the March 29, 2012 episode of Late Show with David Letterman and the April 6, 2012 episode of the Today Show.
Kazee won the 2012 Tony Award for Best Performance by a Leading Actor in a Musical. Kazee and the cast of Once won the Grammy for Best Musical Theater Album at the 55th Annual Grammy Awards.
He is featured on Christina Perri's song "A Thousand Years, Pt. 2," which appears on The Twilight Saga: Breaking Dawn – Part 2 (Original Motion Picture Soundtrack).
In 2017 it was announced that Kazee will star in the Broadway stage adaptation of the 1990 film Pretty Woman, opposite Samantha Barks in her Broadway debut. The musical, titled Pretty Woman: The Musical is directed by Jerry Mitchell and is expected to premiere in Chicago in March 2018 and to open on Broadway in July 2018. After performing as Edward in the Chicago production, Kazee left "Pretty Women" due to family reasons. He was replaced by Andy Karl, who took over the role when the production debuted on Broadway.