Cash's television appearances include Brotherhood, Law & Order, Law & Order: Special Victims Unit, Law and Order: Criminal Intent, Mercy, and The Newsroom. Cash was also a series regular in the 2011 Fox comedy Traffic Light, which ran for one season. She currently stars in the FX Network series You're the Worst as Gretchen Cutler. She received critical acclaim for her performance, with the website The A.V. Club calling her acting in the second season "the best TV performance of 2015".