She was seen by Director Jace Alexander when she performed in a Neighborhood Playhouse school showcase, which led to her appearances in Law & Order and Rescue Me. While on hiatus between the 2004 and 2005 seasons of Rescue Me, she starred as Helen, the sweet-faced, plus-size librarian in Neil LaBute's 2004 play Fat Pig, for which she won a Theatre World Award for 'Outstanding Off-Broadway Debut', as well as receiving nominations for both a Lucille Lortel Award and an Outer Critics Circle Award. She also appeared in a Broadway revival of The Ritz in 2007. Atkinson's film and television credits include Inside Man, Margot at the Wedding, Another Gay Movie, Law & Order and Rescue Me.