Hill was born in Miami, Florida, and raised in Santa Monica, California, where he spent most of his life. He studied business administration at the University of Southern California from 1945 to 1947 before leaving to pursue motorsport, initially working as a mechanic on other drivers' cars. He began driving in club events from 1949 and went to England as a Jaguar trainee that same year. His ability in sports cars brought him to the attention of Enzo Ferrari's team, and he signed with Ferrari in 1956.
Hill's early professional years were spent almost entirely in sports car and endurance racing, where he excelled. Paired with Belgian teammate Olivier Gendebien, he became the first American-born winner of the 24 Hours of Le Mans in 1958, driving through horrific rainy conditions for much of the night. He and Gendebien would win Le Mans twice more, in 1961 and 1962.
Hill made his Formula One debut at Reims in 1958 driving a Maserati. He began driving full-time for Ferrari's Formula One team in 1959, earning three podium finishes and fourth place in the Drivers' Championship. In 1960 at Monza, he won the Italian Grand Prix — the first Grand Prix victory by an American driver in nearly 40 years, excluding the Indianapolis 500, and notably the last Grand Prix win ever achieved by a front-engined car in the World Championship.
The 1961 season brought Hill to the pinnacle of the sport. He won the Belgian Grand Prix and entered the Italian Grand Prix at Monza trailing only his Ferrari teammate Wolfgang von Trips in the championship standings. The race turned tragic: von Trips crashed on the second lap, killing the German driver and 15 spectators. Hill won the race and with it the World Championship, but the circumstances cast a shadow over the achievement. Ferrari chose not to travel to the United States for the season's remaining round, meaning Hill could not race at his home circuit as newly crowned champion. He later reflected that after winning the title he felt a diminished hunger to keep risking his life.
After his final season with Ferrari in 1962, Hill joined the new ATS team founded by disaffected ex-Ferrari engineers. He drove for Cooper in 1964 before retiring from single-seater racing at the season's end, concentrating thereafter on sports cars with Ford Motor Company and Jim Hall's Chaparral Cars.
Hill's endurance record was exceptional even by the standards of an era when the best drivers competed across categories simultaneously. His three Le Mans victories (1958, 1961, 1962), three Sebring wins (1958, 1959, 1961, plus a class win in 1955), and 1964 Daytona victory made him the first driver to complete the Triple Crown of endurance racing — a distinction recognized by the ACO and endurance racing historians. He also won the Targa Florio in 1960 and the 1000 km of Buenos Aires three times.
Hill's final race win came in the 1967 BOAC 500 at Brands Hatch in England, driving for Chaparral. He retired from racing altogether that year.
Following his racing career, Hill built a highly regarded classic car restoration business, Hill and Vaughn, in the 1970s. He worked as a television commentator for ABC's Wide World of Sports and contributed extensively to Road and Track magazine, writing road tests and historical retrospectives over many years. He was a regular judge at the Pebble Beach Concours d'Elegance, appearing at the event 40 times through 2007.
Hill died on August 28, 2008, from complications of Parkinson's disease, having been taken ill after attending the Monterey Historic Automobile Races.
Hill was inducted into the Motorsports Hall of Fame of America in 1989 in the inaugural class and into the International Motorsports Hall of Fame in 1991. He remains one of only two Americans to have won the Formula One World Drivers' Championship, alongside Mario Andretti. His 1960 Italian Grand Prix victory marked a historic boundary — the last win for a front-engined car in Formula One — and his 1961 championship remains the only Formula One title won by an American driver born in the United States.