After graduating from Baylor University in 1993, she got an internship with Late Night with Conan O'Brien, working for Max Weinberg. She then moved to Los Angeles and took improvisation classes with The Groundlings and Improv Olympic.

Following a one-woman show at Improv Olympic, she was an operator at 1-800-Dentist and made small one-episode appearances in various sitcoms. She voiced another Angela on two episodes of King of the Hill. In early 2005, she auditioned for the role of receptionist Pam Beesly for the American version of The Office. After producers told her she was "a little too feisty for Pam," she was called back to audition for the Angela Martin role, which she won. In June 2007, Kinsey shared in a Daytime Emmy Award for Outstanding Broadband Program - Comedy, for her work on The Office: Accountants webisodes.

Kinsey is one of several castmembers of The Office to have a role in License to Wed, a film directed by Ken Kwapis, who often directs episodes of The Office.

Kinsey updates her MySpace blog with behind-the-scenes anecdotes of upcomings episodes of the series. She has also taken to organizing Office cast outings: "I remember watching Friends and thinking, 'They really enjoy each other.' We, in fact, hang out".