She earned her Bachelor of Fine Arts degree from Howard University in 1997. She then attended the Juilliard School's Drama Division as a member of Group 30 (1997–2001), which also included actors Lee Pace and Anthony Mackie.
She was featured in the 2002 Comedy Central film Porn 'n Chicken and the 2004 films Brother to Brother and The Warrior Class. Thoms appeared in the 2006 film version of The Devil Wears Prada as Lily. Thoms has completed filming on the City Lights Pictures movie Descent along with Rent co-stars Wilson Jermaine Heredia and Rosario Dawson and will soon begin filming Jimmie with co-stars Vanessa Williams and Brian McKnight. She appeared in Quentin Tarantino's Death Proof, alongside Zoë Bell, Rosario Dawson and Mary Elizabeth Winstead.
Thoms made her Broadway debut in Regina Taylor's Drowning Crow. She has also appeared in several off-Broadway and regional productions, including Up Against the Wind (New York Theater Workshop), The Oedipus Plays (The Shakespeare Theater), A Raisin in the Sun (Baltimore CenterStage) Joe Turner's Come and Gone (Missouri Rep), The Exonerated (Off Broadway's The Culture Project) and The Antigone Project (The Women's Project). On July 18, 2008, she joined the final cast of Rent starting July 26, 2008, reprising the character of Joanne, replacing Merle Dandridge. The final performance was made into a DVD: Rent: Filmed Live on Broadway.
In the fall of 2010 she appeared in the concert revue For The Record: Quentin Tarantino in Los Angeles, presented by ROCKLA for Show at Barre. It ran from August 12, 2010, to October 30, 2010, and also starred Jenna Leigh Green, Autumn Reeser, Ty Taylor, and Audra Mae. From November 2010 through January 2011, Thoms starred in Show At Barre's For The Record: John Hughes, alongside Barrett Foa, Von Smith and Ty Taylor. In 2011 she appeared at Show At Barre in the revue For the Record: Baz Luhrmann, from February 12, 2011, to June 30, 2011, with Jenna Leigh Green, Arielle Jacobs, Tinuke Oyefule and Kate Reinders.
Thoms reprised her role as Joanne for another production of Rent, directed by Neil Patrick Harris, at the Hollywood Bowl from August 6–8, 2010.
Thoms had a role in the 2014 version of Annie, playing Annie's "fake mother", a character based on Lily St. Regis in the original musical.
In 2016 she appeared in the Broadway revival of Falsettos as Dr. Charlotte.
