Pace has been featured in film, stage and television. He is best known for his role as Calpernia Addams/Scottie in the 2003 Showtime movie Soldier's Girl.

Pace was born in Chickasaw, Oklahoma. As a young child, Pace spent several years in the Saudi Arabia (where his father was in the oil business), and they later moved to Houston. He temporarily quit high school to act at Houston's Alley Theatre before returning to graduate. During his time at the Alley he was in productions of The Spider's Web and The Greeks.

In 1997, Pace was accepted to the Juilliard School's drama division. While there he acted in several plays including, Romeo and Juliet as Romeo, Richard II in the title role and Julius Caesar as Casius, among others. He eventually graduated with a BFA.

After graduation, Pace starred in several off-Broadway plays including: The Credaux Canvas and The Fourth Sister. He also starred in a production of Small Tragedy by Craig Lucas, which is being adapted into a 2007 film (see Small Tragedy). For this role, he was nominated for a Lucille Lortel Award for Outstanding Actor. In 2006, Pace starred in the two-character play Guardians by Peter Morris. Guardians earned Pace his second nomination for a Lucille Lortel Award Outstanding Actor.

Pace first gained recognition for his role in the 2003 film Soldier's Girl. Pace played the central role of Calpernia Addams/Scottie, a transgendered woman dating Army soldier Barry Winchell (played by Troy Garity). Winchell was subsequently murdered because of his sexuality and his relationship with Addams. Of the role, Pace said:

"Not even my excellent training at Juilliard prepared me for my first movie role, where I played a transsexual who falls in love with a military guy in Soldier's Girl. Here I was, this 6'3" 190-pound lanky kid from Chickasaw, Oklahoma, not knowing how to begin being a woman. So I saw documentaries about transsexuals, I lost twenty-five pounds, and I put on prosthetic boobs and hips to become that character. There were times I'd look in the mirror and wonder 'what am I doing to my life here? My dad is going to kill me!' But the reason I went into acting was to be able to play parts as complicated and important as this one. In playing a transsexual, I got the chance to help change people's perspective about other people and that is a powerful thing. I'm playing a swashbuckling bandit in my next film, but I'll always be proud of Soldier's Girl."

Pace won a Gotham Award for Breakthrough Actor and was nominated for several other awards, including a Golden Globe, for his work in this film.

Pace's most recognizable television role was as Aaron Tyler in the acclaimed, short-lived 2004 television series Wonderfalls. He also appeared on Law & Order: Special Victims Unit.

Pace has been cast in the lead role for a new series on ABC for fall 2007. Entitled Pushing Daisies, the show pairs Pace with Pushing Daisies executive producer and co-creator Bryan Fuller. The two previously worked together on Wonderfalls, which Fuller co-created.