Preston has worked on numerous projects with her husband, actor Michael Emerson, whom she married in 1998.[4] Emerson played Ben Linus on television's Lost, and Preston was a guest star in episode 20 of season 3, "The Man Behind the Curtain" as Ben's mother Emily in flashback scenes, though she and Emerson never shared scenes together. The couple were featured in the 2004 comedy film Straight-Jacket and the 2008 feature film, Ready? OK!. She appeared in several episodes of Person of Interest as Grace Hendricks, the former fiancée of Emerson's character, Harold Finch.
Preston later had a recurring character in the 2014 second season of the Kevin Bacon-led thriller, The Following. She portrayed Judy, a prostitute and ill-fated groupie of Joe Carroll.[8] Preston has appeared in a number of films as a supporting character. Including several critically acclaimed films such as Doubt and Duplicity, where she starred alongside stars such as Meryl Streep, Viola Davis, Clive Owen, and Julia Roberts.
Preston was then cast in the drama-comedy Claws playing Polly Marks (Polly-Pol), a mild-mannered preppy with an "ankle bracelet" who recently served time in prison for identity theft.[9] The series was greenlit for a 10-episode first season.[10]
In 2016, Preston reprised her role as Elsbeth Tascioni on The Good Wife spin-off The Good Fight.[11]
In 2023, CBS announced a spin-off series, Elsbeth, in which Preston would reprise her role, though as the central character. It was ordered to series on May 9, 2023, and premiered on February 29, 2024. On April 18, 2024, CBS renewed the series for a second season.[12]