Born in Miami, Florida, Hill was raised in Santa Monica, California. He studied business administration at the University of Southern California from 1945 to 1947 before leaving to pursue racing, initially working as a mechanic on other drivers' cars. He went to England as a Jaguar trainee in 1949 and signed with Enzo Ferrari's team in 1956.
Hill was self-described as an introspective figure, at odds with the aggressive sporting world he inhabited. He once said: "I'm in the wrong business. I don't want to beat anybody, I don't want to be the big hero. I'm a peace-loving man, basically." Those qualities did not prevent him from being exceptionally quick in racing cars.
Hill made his Formula One debut at the French Grand Prix at Reims in 1958, driving a Maserati. He joined Ferrari's Formula One team full-time in 1959, earning three podium finishes and fourth place in the Drivers' Championship. In 1960 he won the Italian Grand Prix at Monza — the first Grand Prix victory for an American driver in nearly forty years, and the last win for a front-engined Formula One car.
The 1961 championship came down to the final race at Monza. Hill entered the Italian Grand Prix trailing only his Ferrari teammate Wolfgang von Trips in the standings. On the second lap, von Trips was involved in a collision that killed him and fifteen spectators. Hill won the race and clinched the championship, though the triumph was deeply complicated by the tragedy. Ferrari's decision not to travel to the United States for the season's final round meant Hill was unable to race in his home event as the newly crowned world champion.
The emotional aftermath changed Hill profoundly. He later reflected: "I no longer have as much need to race, to win. I don't have as much hunger anymore. I am no longer willing to risk killing myself." After his final Ferrari season in 1962, Hill drove for the short-lived ATS team formed by ex-Ferrari engineers, then raced for Cooper in 1964 before retiring from Formula One at the end of that season. His last Formula One start was the 1966 Italian Grand Prix at Monza, driving for Dan Gurney's All American Racers team, in which he failed to qualify.
Hill's greatest and most sustained record was built in long-distance sports car racing, entirely with Ferrari. He won the 24 Hours of Le Mans three times — in 1958, 1961, and 1962 — co-driving with Belgian teammate Olivier Gendebien on all three occasions. His 1958 victory made him and Gendebien the first American-born winners of the race; Hill drove most of the night in heavy rain.
He also won the 12 Hours of Sebring four times: in the 3.0-litre class in 1955, and outright in 1958, 1959, and 1961. When he won the 24 Hours of Daytona in 1964 with the North American Racing Team, Hill became the first driver to win all three major American and European endurance events — a feat later codified as the Triple Crown of endurance racing. He continued sports car racing after leaving Formula One, his final victory coming in the 1967 BOAC 500 at Brands Hatch, driving for the Chaparral team.
In 1959 Hill also drove the experimental MG EX-181 on the Bonneville Salt Flats, reaching 257 mph and breaking the previous record set by Stirling Moss in the same car.
Hill built an award-winning classic car restoration business called Hill and Vaughn with business partner Ken Vaughn. He also worked as a television commentator for ABC's Wide World of Sports, wrote extensively for Road and Track magazine, and judged at the Pebble Beach Concours d'Elegance on more than forty occasions — by 2007 he had judged the event 40 times.
In his later years Hill developed Parkinson's disease. He died on August 28, 2008, at Community Hospital of the Monterey Peninsula following a short illness. His son Derek raced in International Formula 3000 in the early 2000s.
Hill was inducted into the Motorsports Hall of Fame of America in the inaugural 1989 class, the International Motorsports Hall of Fame in 1991, and the West Coast Stock Car Hall of Fame in 2022. Turn 9 of the CW13 configuration at Buttonwillow Raceway Park is named after him. He and Mario Andretti remain the only two American drivers to have won the Formula One World Championship; Hill is the only one born on American soil.