Whitaker was born in the Los Angeles neighborhood of Van Nuys, the fifth of eight children of Thelma and John O. Whitaker, Sr.
Whitaker began his professional acting career at the age of three by appearing in a television commercial for a local used car dealer. He went on to appear in ads for Mattel Toymakers, for such toys as Larry the Lion and Crackers the Parrot in their Animal Yackers series. In 1965, Whitaker originated the character of the young Scotty Baldwin in the soap opera General Hospital. In 1966, he acted in a major feature film, The Russians Are Coming, the Russians Are Coming, which also starred Brian Keith, the actor who would later play Whitaker’s uncle in the television series Family Affair. Family Affair aired from 1966 to 1971. It co-starred Whitaker playing the role of an orphaned boy named Jody Davis, living in a high-rise apartment in New York City with his twin sister Buffy (Anissa Jones) and older sister Cissy (Kathy Garver), his bachelor uncle Bill Davis (Brian Keith), and Bill’s gentleman’s gentleman, Mr. French (Sebastian Cabot). While a regular on the show, Whitaker also starred in the Hallmark Hall of Fame production The Littlest Angel alongside Fred Gwynne and Tony Randall, and an episode of the long-running western The Virginian in 1969. Also, in 1969, Whitaker was a guest-star playing Jack in the S06E01 episode of Bewitched titled “Samantha and the Beanstalk”. In 1970, Whitaker played the part of Willie in a Green Acres episode titled “The Confrontation”. Later, he played Dinky Watson in a Green Acres episode titled “The Beeping Rock”. After Family Affair, he appeared in a two-part episode of Gunsmoke in 1971. Whitaker went on to star in the 1973 Sid and Marty Krofft Saturday morning children’s series Sigmund and the Sea Monsters alongside Billy Barty and Scott Kolden, as well as appeared in feature films, including Disney’s Snowball Express (1972), The Biscuit Eater (1972), Napoleon and Samantha (1972), and The Magic Pony (1977). His most prominent feature film role during this period was the lead in the musical version of Tom Sawyer (1973). In an interview with Tom Snyder on The Late Late Show, Whitaker said he briefly worked as a computer consultant at CBS. He later joined a Los Angeles talent agency, Whitaker Entertainment, owned by his sister. Whitaker also was Dana Plato’s manager. In 1999, Whitaker received the Young Artist Former Child Star Lifetime Achievement Award at the 20th Youth in Film Awards. In 2012, Whitaker co-produced and co-hosted a short-lived radio talk show, The Dr. Zod and Johnny Show. In 2016, Whitaker gave a guest star cameo appearance in Amazon’s reboot of Sigmund and the Sea Monsters. In the premiere episode, he played the part of a heckling boat owner Zach, against David Arquette’s salty sea captain character, Captain Barnabas. The episode had a similar cameo appearance by original show creators, Sid and Marty Kroftt.