Delfino was cast in MGM's Zeus & Roxanne before winning the role of Tina Dimeo in NBC's The Tony Danza Show, where she played Danza's teenage daughter. After playing Natalie Sanford in the independent film The Secret Life of Girls, Delfino was cast as Maria DeLuca on Roswell. On hiatus, she performed in the small role of Vanessa in Traffic. She also acted in Reeseville, Celeste in the City, R.S.V.P. and State's Evidence.
Delfino starred in a number of episodes of the NBC show Quarterlife, also shown on MySpaceTV, which started airing November 11, 2007. In 2011, she starred with Raven-Symoné in the show State of Georgia on ABC Family until its cancellation.
Delfino performed in ABC's pilot The Family Trap starring Mandy Moore and Stockard Channing. She was eight months pregnant with her first child during the shooting, so director Shawn Levy shot around the pregnancy for the entire project. One month after giving birth, Delfino was cast as Dwight Schrute's sister on NBC's The Office attempted spin-off, The Farm. NBC did not greenlight the series.
