According to Disney, Funicello died at Mercy Southwest Hospital from complications due to multiple sclerosis, a disease she was diagnosed with in the late 1980s.
Born Oct. 22, 1942, Funicello and her family moved to the San Fernando Valley when she was four years old. She was discovered by Walt Disney while dancing the lead in Swan Lake at the Starlight Bowl in Burbank.
Funicello could be considered the first of Disney's break-out kid stars. She hit the national spotlight at the age of 13 on "The Mickey Mouse Club." She was one of the last kids chosen for the show, but quickly became the most popular Mousketeer during the three years she was on the TV hit.
"Annette was and always will be a cherished member of the Disney family, synonymous with the word Mousketeer, and a true Disney Legend," said Disney CEO Bob Iger in a statement. "She will forever hold a place in our hearts as one of Walt Disney's brightest stars, delighting an entire generation of baby boomers with her jubilant personality and endless talent."
From "Mickey Mouse Club," Funicello catapulted to the big screen, always playing the wholesome girl next door. Her greatest success came in a series of beach movies with Frankie Avalon. There was the 1965 "Beach Blanket Bingo," ''Bikini Beach," and "How to Stuff a Wild Bikini." The formula was always the same: Frankie and Annette would break up but eventually get back together.
"She was an amazing girl," Avalon said. "It's like losing a family member. I'm devastated, but I'm not surprised."
She also was a recording star, producing over a dozen albums and hit singles such as "Tall Paul" and "Pineapple Princess." But she credited it all to the big break Walt Disney himself gave her.
"Because of those ears and Walt Disney, wonderful things happened," she said.
Funicello saw the first insidious sign of multiple sclerosis when she had trouble walking during filming for "Back to the Beach" in 1987. When it was diagnosed, she later recalled, "I knew nothing about (MS), and you are always afraid of the unknown. I plowed into books."
Her symptoms were relatively mild at first, but gradually she lost control of her legs, and she feared people might think she was drunk. So she went public with her ordeal in 1992. The illness eventually forced her into a wheelchair.
"Throughout all the years we were friends, she never changed from that sweet person who cared so much about others. She always had time for everyone; family, friends and fans alike," said fellow Mouseketeer and longtime friend Sharon Baird. "It's no wonder she was America's sweetheart."
Disney is the parent company of ABC7.
The Associated Press contributed to this report.