She is known for her roles in Rent, Cold Case, The Devil Wears Prada, Death Proof, the Fox television series Wonderfalls; as of 2018 she has been a recurring cast member of the police and firefighter TV drama 9-1-1.

[5] 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.

Thoms has appeared in several movies, most notably in the film adaptation of the Broadway musical Rent in which she plays Joanne Jefferson, lawyer and lover of Maureen Johnson (Idina Menzel).

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.

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.