Hayden Panettiere was born in and partly raised in Palisades, New York, the daughter of Lesley R. Vogel, a former soap opera actress, and Alan L. "Skip" Panettiere, a fire department lieutenant. Panettiere is of Italian descent, her surname meaning "baker" in Italian. She has one younger brother, fellow actor Jansen Panettiere.
Although Hayden Panettiere attended South Orangetown Middle School in New York, she was homeschooled from grade nine to the completion of high school. For now, Hayden Panettiere is postponing higher education in favor of an acting career.
Hayden Panettiere first appeared in commercials at 11 months, beginning with an advertisement for Playskool. She landed a role as Sarah Roberts on the ABC soap opera One Life to Live (1994–1997), and she followed that up by playing the part of Elizabeth "Lizzie" Spaulding on the CBS soap opera Guiding Light (1997–2000). While on Guiding Light, Panettiere's character Lizzie battled leukemia. For drawing the attention of daytime viewers to the disease, and for improving national awareness, the Leukaemia & Lymphoma Society gave her its Special Recognition Award.
For her performance in Lifetime Television's 1999 TV movie If You Believe, she was nominated for the Young Artist Award for Young Actress Age Ten or Under in the category of Best Performance in a TV Movie or Pilot. Hayden Panettiere appeared on Fox's Ally McBeal as the title character's daughter, had a recurring guest role on Malcolm in the Middle and guest starred in Law & Order: Special Victims Unit.
Hayden Panettiere became most prominent as Claire Bennet in the NBC series Heroes, which was created by Tim Kring, as a high school cheerleader with regenerative healing powers. Thanks to her role on Heroes, she became a regular on the science fiction convention circuit, invited to attend conventions around the world in 2007, including Gen Con, New York Comic-Con, and Fan Expo Canada. Hayden Panettiere has complained that her acting options are sometimes limited because "people look at her as either the 'popular cheerleader' type or just 'the blonde.'"
In early 2007, Hayden Panettiere appeared on the MTV show, Punk'd. The appearance was engineered by her mother and involved a male "fan" discussing her work with her, instigating a jealous reaction from the man's spouse.
Hayden Panettiere has appeared in over a dozen full-length feature films.
In 1998, she provided the voice for Dot in A Bug's Life. She played the role of Coach Yoast's daughter, Sheryl, in the 2000 Disney film Remember the Titans. She also starred in Bring It On: All or Nothing as a cheerleader and had a supporting role as Adelaide Bourbon in the independent film Shanghai Kiss. In 2004, she appeared in the Disney Channel film Tiger Cruise, and in Raising Helen as Kate Hudson's adolescent niece. In 2005, she was the title character's rival in a skating contest in Ice Princess. In the same year she starred in the film Racing Stripes where she played the character Channing Walsh.
In June 2007, she signed with the William Morris Agency, after previously being represented by United Talent Agency. Forbes estimated that she earned $2 million in 2007.
In 2008, Hayden Panettiere appeared in the drama Fireflies in the Garden as a younger version of Emily Watson's character, Jane Lawrence. In September 2008, she appeared in a satirical video, a mock-PSA (public service announcement) on funnyordie.com entitled "Hayden Panettiere PSA: Your Vote, Your Choice." Again, in October, Hayden Panettiere appeared in another satirical PSA video on funnyordie.com entitled "Vote for McCain: He's just like George Bush, except older and with a worse temper."
In 2011, she replaced Anne Hathaway as the voice of Red for the animated sequel Hoodwinked Too! Hood vs. Evil. In April 2011, Hayden Panettiere appeared in the sequel of the Scream franchise, Scream 4. She played Kirby Reed, alongside Emma Roberts and Rory Culkin.
Hayden Panettiere voices Kairi in the Kingdom Hearts series of video games created by Square Enix. She also voiced as Xion in the secret ending of Kingdom Hearts Birth By Sleep replacing Alyson Stoner.
Hayden Panettiere was nominated for a Grammy in 1999 for A Bug's Life Read-Along (2000). In 2004, she recorded a song entitled "My Hero Is You" with a video for the Disney Channel film she starred in, Tiger Cruise. The next year she recorded a song entitled "I Fly" for the Disney film Ice Princess in which she also co-starred. She recorded a song for the Hollywood Records compilation Girl Next (2006) and another song entitled "Go to Girl" for Girl Next 2 (2007). Also in 2007, She also recorded a cover for "Cruella De Vil" for DisneyMania 5, "Try" for the Bridge to Terabithia soundtrack and a ballad called "I Still Believe" for Cinderella III: A Twist in Time.
Panettiere's first single, "Wake Up Call", was digitally released on August 5, 2008. A clothing brand named Candie's announced that it was premiering an ad campaign for the single in late July. Similarly, Candie's would also provide additional promotion for the single with a television advertisement and a music video.