Sweeten was born in Brownwood, Texas, to Timothy Lynn Sweeten and Elizabeth Anne Millsap. She is perhaps best known for playing the role of Ally Barone on the CBS television sitcom Everybody Loves Raymond from 1996–2005. Her younger twin brothers Sullivan and Sawyer aka "The Bubs" played her twin brothers Geoffrey and Michael Barone on the sitcom.
Sweeten began her acting career by attending the Kay Scott School of Performing Arts in San Saba, Texas, at age 3. While attending Kay Scott, Sweeten, at age four, was cast in the television movie A Promise to Carolyn. From there, she went on to book several commercials in Dallas. Later that year, she auditioned for several television pilot roles in Los Angeles and was discovered by producers of Everybody Loves Raymond. Sweeten played Ally Barone, the eldest daughter of Raymond Barone for 9 seasons, starting in 1996, until the show's end in 2005.
While building her television career, Sweeten has also been involved in several feature films. These include The Christmas Path, A Dog of Flanders, a voice-over on Toy Story 2 and the critically acclaimed film and winner of the 2003 Sundance Film Festival Grand Jury Prize, American Splendor. Her hobbies are playing guitar and singing.