After graduating from Juilliard, Brooks won roles in two theater productions: the Shakespeare Theatre Company's Servant of Two Masters, and Blacken the Bubble. She left both productions in 2013 to join the cast of the Netflix-produced television series Orange Is the New Black, a show about a women's prison based on Piper Kerman's memoir of the same name, as Tasha "Taystee" Jefferson. Her character Taystee was originally intended to be featured in the show for only two episodes, but ended up being written into the rest of the first season. Taystee's on-screen best friend is played by Samira Wiley, with whom Brooks has been friends since they met while studying together at Juilliard. Brooks' performance in Orange Is the New Black has been praised by critics, with one writer from The Daily Beast calling her "the breakout actress of the show and one of the most refreshing and exciting new talents of 2013". Brooks was upgraded from a recurring cast member to a series regular for the show's second season.
In September 2013, Brooks was cast in an upcoming episode of the HBO series Girls, where she will play the first black woman on the show.