The Bel Ami actress has signed on for a major story arc on the show, though it is unclear in how many episodes she will appear.
Thurman will play "a famous and somewhat difficult movie star who flirts with the idea of starring in Marilyn", the musical upon which Smash is based.
The series stars Katharine McPhee, Anjelica Houston and Debra Messing. It is produced by Steven Spielberg.
Smash will premiere on Monday, February 6 at 10/9c.
In June, Smash signed a deal with Columbia Records for rights to the music from the first season.
Watch Smash's first music video, featuring McPhee, below: