Tiffany made her television acting debut in the pilot episode of the Fox sitcom, Quintuplets where she then went on to appear in television shows such as, 8 Simple Rules, American Dreams, The O.C., Desperate Housewives, That's so Raven, Jericho, Wizards of Waverly Place and Disney Channel hit show Hannah Montana.
In 2009, Thornton co-starred as Tawni Hart on the Disney Channel Original Series: Sunny With a Chance. Thornton then went on to reprise her role as Tawni in the Disney Channel Original Movie: Hatching Pete.
As of 2017, Thornton's main role is playing Mom to her two children, Kenneth and Bentley. Outside of raising her two sons, Thornton is a blogger for DisneyBaby.com, a radio personality for KLAZ 105.9 and also co-hosts the morning radio show "Kramer and Tiffany".