Cuoco was born in Camarillo, California to Gary Carmine Cuoco and Layne Ann Wingate. Her acting career began in 1992 with the TV movie, Quicksand: No Escape. Her role as Marcia Brady on Growing Up Brady in 1999 brought her much attention, as well as a role on the CBS sitcom, Ladies Man. In 2004, in addition to her role on 8 Simple Rules she has had starring roles on the NBC miniseries 10.5, on the ABC Family original movie Crimes Of Fashion, and in the independent film Debating Robert Lee.

In 2004, Cuoco was named #74 on FHM-US's 100 Sexiest Women 2004. She began voicing the character of "Brandy" on the Disney Channel's cartoon, Brandy and Mr. Whiskers, later on that same year. Cuoco is currently starring as Billie Jenkins, a new witch in the 8th season of Charmed. She parodied herself on one episode of "8 Simple Rules" in a cold opening sequence.

After she was tricked by Ashton Kutcher's crew members on Punk'd Season 3 Episode 3, Cuoco has announced that she will team up with a total of at least 160 victims (at the start of season 7, including Yankees' Third Baseman Alex Rodriguez and soon-to-be-cancelled Alias star Michael Vartan), and other non-victims threatned to get punk'd by Kutcher or his crew members (including New England Patriots QB Tom Brady, The Apprentice's Donald Trump, CSI: NY's new comer Anna Belknap, Yankees' outfielder Hideki Matsui, Wings' Forward Pavel Datsyuk to name some), to create a new show called Get Ashton.