Born in Luton, Bedfordshire, Read worked as an apprentice fitter before taking up amateur short-circuit racing in 1958. He won the Junior Manx Grand Prix in 1960 on a Manx Norton at record speed, followed by victory in the Junior (350cc) TT in 1961. He was a two-time winner of the Thruxton 500 endurance race in 1962 and 1963. In 1963 he was drafted into the Scuderia Duke Gilera team to cover for the injured Derek Minter, finishing third at the Isle of Man Senior TT behind race winner Mike Hailwood.
Read joined Yamaha in the mid-1960s alongside Canadian Mike Duff and later Bill Ivy. In 1964 he gave Yamaha their first world title, winning the 250cc championship and repeating the achievement in 1965. Yamaha's new four-cylinder 250cc machine in 1966 suffered teething problems, and Read lost the crown to Hailwood. In 1967 he battled Hailwood's six-cylinder Honda all the way to the final round, ending tied on points but losing the title due to fewer wins.
The 1968 season became controversial. Yamaha wanted Read to target the 125cc title and leave the 250cc to teammate Bill Ivy. Read defied team orders and contested both, winning the 125cc championship and then claiming the 250cc title on elapsed time after finishing level on points with Ivy. Yamaha never offered him another factory ride as a result.
After sitting out much of 1969 and 1970 when the major Japanese manufacturers withdrew from Grand Prix racing, Read returned full-time in 1971 on a specially developed privateer Yamaha with twin disc brakes and improved aerodynamics. He won the first three Grands Prix of the season and clinched his fifth world championship.
In 1972, Read accepted an offer to join the MV Agusta factory team in the 350cc class to assist reigning champion Giacomo Agostini against the growing two-stroke challenge from Yamaha. He took victory at the 350cc East German Grand Prix and helped Agostini defend the title.
In 1973, Read and Agostini were paired again in both the 350cc and 500cc classes. The championship was upended when Jarno Saarinen — who had led the 500cc standings — was killed in the tragic accident at the Nations Grand Prix that also claimed Renzo Pasolini. Yamaha withdrew their team out of respect, and without significant opposition, Read won his first premier-class world championship. His victory was notable for being the first 500cc title won by a motorcycle using Lockheed disc brakes.
Agostini departed for Yamaha in 1974, leaving Read as MV Agusta's lead rider. He successfully defended the 500cc title with four Grand Prix victories, a season hampered for rival Agostini by injuries and mechanical problems. Read's 1974 title was also the last world championship for MV Agusta and the last time a four-stroke machine won a premier-class title until the introduction of MotoGP in 2002. In 1975, Read pushed Agostini and his Yamaha hard but finished second in the championship; FIM scoring rules of the time counted only the best six of ten results, leaving him as runner-up despite accumulating more raw points. Recognising the growing dominance of two-stroke machinery, he left MV Agusta and campaigned a privateer Suzuki RG 500 in 1976 before retiring from Grand Prix racing.
Read returned to the Isle of Man TT from 1977, winning the Formula 1 race on a works Honda CB750 SOHC and the Senior race on a Suzuki that year. Honda subsequently produced a limited run of 150 Phil Read Replica roadsters based on the CB750F2. His final TT appearance came in 1982 at age 43.
Read's TT involvement was not without controversy. Following the death of Gilberto Parlotti at the 1972 event, Read joined teammate Agostini and a number of other leading riders in publicly criticising the safety of the Snaefell Mountain Course. His stance contributed to the FIM removing the Isle of Man from the World Championship calendar after 1976, which brought him significant hostility from the island's fans. He maintained that his position concerned riders being contractually compelled to race there rather than having a free choice. In later years both Read and Agostini regularly returned to the TT as guests on exhibition and parade laps.
Phil Read's seven world championships span three engine classes — an achievement unique in the sport at the time. He was among the last riders to win a premier-class title on a four-stroke machine before the MotoGP transition, and his clashes with Mike Hailwood and his later defiance of Yamaha team orders added to his reputation as a forceful, independent competitor. He was appointed MBE in 1979 for services to motorcycle racing.