He made his debut in the 1985 musical film Krush Groove and from 1987 to 1994 starred as attorney Jonathan Rollins in the NBC legal drama series L.A. Law.

Underwood has appeared in a number of films during his career, including Just Cause (1995), Set It Off (1996), Deep Impact (1998), Rules of Engagement (2000), Something New (2006), Madea's Family Reunion (2006), Juanita (2019), and Longlegs (2024).

[3][4][5] Underwood lived on bases and Army Posts in the United States and Stuttgart, Germany throughout his childhood due to his father's military career.

[7] He went on to attend the Carnegie Mellon School of Drama in Pittsburgh, Pennsylvania, and is an honorary member of the Phi Beta Sigma fraternity.

After his film debut, Krush Groove, Underwood's 1985 appearance on The Cosby Show landed him a short stint for three months on the ABC soap opera One Life to Live as Bobby Blue.

[8] He later co-starred in the short-lived CBS crime drama series Downtown from 1986 to 1987, and guest-starred on Scarecrow and Mrs. King and 21 Jump Street.

After L.A. Law, he starred in a number of movies, In 1995 he appeared in the legal thriller Just Cause, and the following year played Jada Pinkett's love interest in the heist film Set It Off.

[11] In 2003, he guest starred in four episodes[6] on the HBO series Sex and the City playing Cynthia Nixon's love interest.

In 2004, he played the role of Roger De Souza opposite Heather Locklear in NBC short-lived drama LAX.

He had a recurring role as the sexy grade school teacher in the CBS sitcom The New Adventures of Old Christine opposite Julia Louis-Dreyfus from 2006 to 2008.

[24] In January 2020, Underwood appeared on stage as Captain Richard Davenport in the Roundabout Theatre Company's Broadway revival of Charles Fuller's Pulitzer Prize-winning drama A Soldier's Play.