Zito grew up near Aqueduct Racetrack in Queens, New York and went to the track with his father starting when he was about nine years old. Rules at the time prevented him from entering the grounds so he'd spend the day with a security guard. His first job on the track was as a hotwalker while still a teenager. He moved on to become a groom for trainer Buddy Jacobson and then worked for trainer Bob Lake. He was an assistant to trainer Johnny Campo for four years and to Hall of Famer LeRoy Jolley before going out on his own in 1972 at the age of 24.
Zito broke into the business with a claiming stable in the 1970s, working his way from the bottom up. His first winner was Palais at Liberty Bell Park in Philadelphia in December 1972. However, through years of hard work and dedication Zito became a two time Kentucky Derby winning trainer and a trainer of many top horses. The key horse in building Zito's reputation as a top stakes trainer was the colt Thirty Six Red. He selected Thirty Six Red for $92,000 at the Keeneland September yearling sale in 1988 for owner Giles Brophy. In 1990, the colt won the Wood Memorial Stakes, ran second in the Belmont Stakes and was third in the Breeders' Cup Classic.
Zito has won all three legs of the Triple Crown. He captured the Run for the Roses in 1991 with Strike the Gold and in 1994 with Go for Gin, sent out Louis Quatorze to take the 1996 Preakness, stopping Wayne Lukas' streak of six straight Triple Crowns wins, and his two improbable victories in the Belmont Stakes prevented Triple Crown sweeps. Each of his horses went off at odds of 36-1 or more. Birdstone ($74) ended Smarty Jones' Triple Crown bid in 2004, while Da'Tara ($79) scored a 38-1 upset in the 2008 Belmont when Kentucky Derby/Preakness winner Big Brown did not finish the race. "That was too much for words," said Zito after Da'Tara's victory for owner Robert LaPenta. "This doesn't get old."
Zito spends half the year in Saratoga based at the Oklahoma training track and is something of an adopted son of Saratoga Springs, often speaking out about the city's issues and Saratoga Race Course. He has a barn at Belmont Park, and his stable heads south to Florida for the winter. He returns to Saratoga via Kentucky, where he participates in the Keeneland and Churchill Downs meets.