Robin Weigert is best known for her role as Calamity Jane in the HBO series Deadwood, for which she received a 2004 Emmy Award nomination for Best Supporting Actress in a Drama Series. She appeared previously on HBO as the Mormon Mother in the Emmy and Golden Globe-winning Angels in America, directed by Mike Nichols.

On film, Weigert has been featured in The Sleepy Time Gal and Loggerheads. In 2007, she will be seen in the films Reservations and Things We Lost in the Fire, starring Benicio del Toro and Halle Berry. Weigert's other television appearances include guest-starring roles on Lost, Law and Order: SVU, The Unit and Cold Case. She was a recipient of the 2005 Breakthrough of the Year Award from Hollywood Life magazine.

On Broadway, Weigert most recently played the role of Poppy Norton-Taylor in the hit revival Noises Off, and was nominated for Drama Desk and Lucille Lortel awards for her acclaimed turn in Richard Nelson's Madame Melville, with Joely Richardson and Macaulay Culkin. She was also seen in The Seagull in Central Park, with a cast including Meryl Streep, Kevin Klein, Natalie Portman, Phillip Seymour Hoffman and Christopher Walken. Weigert's other theatre credits include Lincoln Center's Twelfth Night; off-Broadway roles in A Place at the Table, Arms and the Man, Hamlet, Goodnight Children Everywhere, Pride's Crossing; and off-off-Broadway appearances in Hamlet, Macbeth and The Three Sisters. She has also performed regionally at McCarter, Arena Stage, Long Wharf, New York Stage and Film, A.C.T. and the Berkshire Theater Festival. Between seasons two and three of Deadwood, Weigert had the opportunity to play the role of Josie in A Moon for the Misbegotten at A.C.T., for which she received a Bay Area Critics Circle Award.