[1] She is best known for playing Natalie "Fig" Figueroa in the Netflix comedy drama series Orange Is the New Black (2013–2019), for which she won a Screen Actors Guild Award for her role as part of the ensemble cast.

She played District Attorney Wendy Parks in the ABC crime-legal drama TV series How to Get Away with Murder and Sunny in the FX comedy Better Things.

In 2014, she also appeared in Season 4 of Masters of Sex on Showtime, as Lilian Izikoff on Rosewood, and Trina in Michael Showalter's TBS series Search Party.

Reiner has appeared in several films, including Kissing Jessica Stein, The Vicious Kind, Arranged, Schooled, That Awkward Moment, and 5 Flights Up.

In 2004, she played the role of Christine Erganian, Thomas Haden Church's character's fiancée, in the film Sideways, which won Screen Actors Guild Award for Outstanding Performance by a Cast in a Motion Picture.