Baio is of Italian descent. In 1976, he played the title character Bugsy Malone in a cult film kiddie musical directed by Alan Parker that also co-starred Jodie Foster with whom he was reunited once again in the 1980 teen girl drama "Foxes" helmed by Adrian Lyne. When he was 16 years old, Baio landed his most famous role as Fonzie's tough little cousin, Charles 'Chachi' Arcola, on the then already popular television show Happy Days. For his charismatic juvenile performance in the series, he received his first Young Artists Award as Best Young Comedian in Television or Motion Pictures, during the Third Annual Youth in Film Awards. In 1982 he starred in a spin-off of Happy Days entitled Joanie Loves Chachi, which lasted only one season. That same year, he appeared opposite future Charles in Charge costar Willie Aames in the film Zapped!, the story of a boy who obtains telekinesis and uses it to "zap" the clothing off of attractive females. Baio made his first album for RCA in 1982. The eponymous album featured such songs as "What was in that Kiss," "How Do You Talk to Girls," and "Wanted for Love." He recorded a second album, The Boys Are Out Tonight, for RCA in 1983. The album feaured songs such as "Some Girls," "She's Trouble," and "Fingerprints". During his Happy Days run, Baio also became known as the star of after school specials such as The Boy Who Drank Too Much and Stoned, which earned him a second Young Artists Award as Best Young Actor in a Television Special. He also received two Emmy Award nominations, for Stoned in 1981 and for All The Kids Do It in 1985. In 1984, after Happy Days ended, Baio starred as a male nanny on Charles in Charge, a show that remained on the air until 1990. Since the end of Charles in Charge, Baio has appeared in various short-lived sitcoms, including Baby Talk (1991) and Rewind, which was picked up by the Fox network in 1998 but was canceled before any episodes aired. Between 1992 and 1995, he played Dr. Jack Stewart in the successful Diagnosis: Murder franchise. He also became a successful television director, working on a variety of programs, and worked for Thirty Second Films, a production firm specializing in TV commercials. Baio also starred in the independent films Very Mean Men, Face to Face (a.k.a. Italian Ties), and The Bread, My Sweet (a.k.a. A Wedding For Bella). Very Mean Men, a gangster comedy involving a mob war between two syndicate families, featured an ensemble cast headed by Matthew Modine, Ben Gazzara, Charles Durning, Burt Young, Louise Fletcher, and Martin Landau. Baio himself enacted the pivotal role of impetuous crime scion Paulie Minnetti, who unwittingly instigates the crime feud. He garnered this laudatory quote from Variety: "a career-reviving turn by Scott Baio with hair dyed blonde and sporting a white goatee." Face to Face, a bittersweet comic drama, tells how three young men (played by Baio, Thomas Calabro, and Carlo Imperato) kidnap their emotionally-distant fathers (played by Dean Stockwell, Alex Rocco, and Joe Viterelli) for a weekend of male bonding. The movie won the Audience Prize for Best Comedy at the Marco Island Film Festival, the Silver Screen Accolade in the Reno Film Festival and the 10 Degrees Hotter Best Feature Award during the Valley Film Festival. Baio also worked as a producer (with his older brother, Steven) on Very Mean Men and as a co-scriptwriter (with Jeffrey Gurian) on Face to Face. The Bread, My Sweet, a gentle romance about love and cooking among Italian-Americans, collected multiple top accolades from the Santa Monica, Stony Brook, Marco Island, Houston Worldfest, and Iowa Hardacre Film Festivals. Baio won three Best Actor Awards for his lead performance as corporate raider/family baker Dominic Pyzola in The Bread, My Sweet from the Atlantic City, Kansas City Halfway to Hollywood and San Diego International Film Festivals. Baio had a recurring role on Arrested Development for the Fox sitcom's third season in autumn 2005, playing the Bluth family's new lawyer, Bob Loblaw (so named because it sounds like "blah blah blah" when spoken). He took over the role of lawyer from his former Happy Days co-star Henry Winkler (Fonzie). Baio appeared in four memorable episodes of the cult show before it finally ended: "Forget Me Now," "Notapusy," "Mr. F," and "Making A Stand."
Baio is also famous for dating several very popular actresses over the years. Among them, his Joanie Loves Chachi co-star Erin Moran, Baywatch actresses Pamela Anderson, Erika Eleniak and Nicole Eggert (the latter co-starring with Baio on Charles In Charge prior to Baywatch); Natalie Raitano, Nicolette Sheridan, Brooke Shields, Denise Richards, and Heather Locklear. Baio twice was engaged to Anderson, but was called off both times. His success with women led to his induction into The Man Show Hall of Fame on July 21, 1999. Unlike many of his fellow actors in Hollywood, Baio is a very conservative Republican. He was a member of Young Americans for Freedom. He was one of the famous guests in attendance at President Ronald Reagan's state funeral. The New York Daily News published Michelle Caruso's article "A Goodbye as the Sun Sets in the West" (dated June 12, 2004), which mentioned Baio, who had been seated near former U.K. Prime Minister and Baroness Margaret Thatcher: "Scott Baio, who played Chachi on the hit sitcom Happy Days, said: President Reagan made me feel proud to be an American. Today, I feel sadness."
More obscurely, Baio has become a recurring character in the online comic strip Goats. In the first South Park episode, Cartman said he had a dream where Baio gave him pinkeye. Two of Baio's TV roles were mentioned in the song "Hey Ladies" by the Beastie Boys. Scott was also mentioned in an episode of Family Guy, when Peter says, "They call this the magic hour. The day's not quite gone, but the night's not quite here and somewhere, Scott Baio is plowing a woman he doesn't love." There is a reference to Baio in an episode of the CBS sitcom Yes, Dear. Greg and Jimmy go clubbing, and they hear that Baio is inside the club performing magic tricks. In a Season 1 episode of the Canadian TV hit show, Trailer Park Boys, while exercising his one-of-a-kind ability to talk his way out of yet another small crime (stealing auto parts), Ricky, Sunnyvale Trailer Park resident, ridicules one of the police officers present by calling him Chachi to which the irritated officer responds, "It's Officer Poole, not Chachi!" There is also a reference in a song "You Gonna Eat Alla That?" by the band Here Come the Mummies: "Hey oh, hey oh...got your meat and two potatoes, hey oh, hey oh white and creamy like Scott Baio." In the online game Kingdom of Loathing, there is an item called the Talisman of Baio. This item is obtained by fighting "The Baiowulf," a monster with the appearance of Baio as a werewolf. Theres a local Grindcore band in Denver named the Scott Baio Army. On the Late Night with Conan O'Brien talk show, Conan O'Brien frequently references Baio as a nostalgic but now presumably obscure celebrity. He often follows such a reference with an a cappella rendition of the first lines of the theme song to Charles in Charge. Christian punk band Relient K have a song named "Charles in Charge" on their self-titled 2000 album.