Marvel appeared in many stage productions throughout her career. She has won Obie Awards for her work in Thérèse Raquin, Hedda Gabler, A Streetcar Named Desire and Misalliance She returned to the role she originated Off-Broadway of Brooke Wyeth in Other Desert Cities, which was played by Rachel Griffiths in its Broadway premiere. She will be coming back to Broadway in the revivial of Picnic. In 2009, for her performance in Fifty Words, she was nominated for a Drama Desk Award for Outstanding Actress in a Play.
In film, Marvel has appeared in True Grit as the adult Mattie Ross, and in Burn After Reading, directed by the Coen brothers. She also appears in the The Bourne Legacy, Lincoln and Hyde Park on Hudson.
On television Marvel is best known for her regular role as Nancy Parras in CBS series The District (2000–2004). She also played recurring roles in Lights Out, Law & Order, Nurse Jackie and Person of Interest, and will guest-starred on 30 Rock, The Good Wife and The Newsroom. In 2013 she was cast as lead role of CW's family drama pilot Blink opposite John Benjamin Hickey.