In 1955, the 12-year-old was discovered by Walt Disney as she performed as the Swan Queen in Swan Lake at a dance recital in Burbank, California. On the basis of this appearance, Disney cast her as one of the original "Mouseketeers". She was the last to be selected, and the only one picked by Walt Disney. She soon proved to be very popular. By the end of the first season of Mickey Mouse Club, she was receiving 6,000 letters a month, according to her Disney Legends biography.
In addition to appearing in many of the Mouseketeers' sketches and dance routines, Funicello starred or co-starred in a number of serials on The Mickey Mouse Club. These included Adventure in Dairyland, her own self-titled serial, Walt Disney Presents: Annette (which co-starred Richard Deacon), and the second and third Spin and Marty serials,The Further Adventures of Spin and Marty and The New Adventures of Spin and Marty. It was in a hayride scene in the Annette serial that she performed the song that was to launch her singing career. The studio received so much fan mail about "How Will I Know My Love", written by the Sherman Brothers, that Walt Disney decided to issue it as a single, and to give Funicello, somewhat unwillingly, a recording contract.
After the Mickey Mouse Club she remained under contract with Disney for a time, with television roles in Zorro, Elfego Baca and The Horsemasters. For Zorro she played Anita Cabrillo in a three-episode storyline, about a teen-aged girl who arrives in Los Angeles to visit a father who does not seem to exist. This role was reportedly a birthday present from Walt Disney, and the first of two different characters played opposite Guy Williams as Zorro. Annette also co-starred in Disney-produced movies such as The Shaggy Dog, Babes in Toyland, The Misadventures of Merlin Jones, and The Monkey's Uncle.
Although uncomfortable being thought of as a singer, Annette had a number of pop record hits in the late 1950s and early 1960s, mostly written by the Sherman Brothers and including: "Tall Paul", "First Name Initial", "O Dio Mio", "Train of Love" (written by Paul Anka) and "Pineapple Princess". Annette also recorded "It's Really Love" in 1959, a reworking of an earlier Paul Anka song called "Toot Sweet"; Anka reworked the song for a third time in 1962 as "Johnny's Theme" and it opened The Tonight Show Starring Johnny Carson on television for the next three decades. In an episode of the Disney anthology television series titled "Disneyland After Dark", Annette can be seen singing live at Disneyland. Walt Disney was reportedly a fan of 1950s pop star Teresa Brewer and tried to pattern Annette's singing in the same style. However, Funicello credits "the Annette sound" to her record producer, Tutti Camarata, who worked for Disney in that era. Camarata had her double-track her vocals, matching her first track as closely as possible on the second recording to achieve a fuller sound than her voice would otherwise produce.
When she was cast in her first beach movie, Walt Disney himself -- for the sake of her virginal image -- asked her not to appear in any provocative scenes or wear any attire that showed her navel. She (perhaps unintentionally) did not fully comply with the latter request. She is seen wearing a two piece fishnet suit in the second film (Muscle Beach Party) and a blue and white bikini in the third (Bikini Beach). Both swimsuits showed her navel, particularly in Bikini Beach, where it is visible extensively during close up shots in a sequence early in the film when she meets Frankie Avalon's "Potato Bug" character outside his tent.
She and Avalon became so iconic as "beach picture" stars that they were re-united in 1987 for Back to the Beach, parodying their own films of two decades earlier. They then toured the country as a singing act.
Funicello announced in 1992 that she suffers from multiple sclerosis. She had kept her condition a secret for many years, but felt it necessary to go public to combat rumors that her impaired carriage was the result of alcoholism. That same year, she was inducted as a Disney Legend. In 1993, she opened the Annette Funicello Fund for Neurological Disorders at the California Community Foundation.
Funicello's best friend is Shelley Fabares. Shelley and Annette have been friends since they were young teenagers, and Shelley was a bridesmaid at Annette's first wedding.
Her autobiography, published in 1994, is A Dream Is a Wish Your Heart Makes: My Story. The title is taken from a song from the movie Cinderella. A made-for-TV movie based on the book, A Dream Is a Wish Your Heart Makes: The Annette Funicello Story, was made in 1995. In the final scene, the actress portraying Funicello, riding in a wheelchair, is turned away from the camera — turning back, it is Funicello herself, who delivers a message to a group of children. During this period she also produced her own line of teddy bears for the Annette Funicello Collectible Bear Company. The last collection in the series was made in 2004.