Born in Pretoria, Byrne graduated with a BSc in engineering from the Witwatersrand University in Johannesburg. Initially he specialized in designing gliders but traveled to Britain in 1973 to help a friend who was racing in Formula Ford 1600. He modified the Royale RP16 so successfully that he was offered a job as chief designer for the company. In 1976 Royale supplied cars to Toleman Motorsport in Formula Ford 2000 and success in 1977 led to Byrne joining the team when it entered Formula 2 in 1978. Initially Toleman used March and Ralt chassis but for 1980 Byrne was given the go-ahead to design Toleman's own car, to be fitted with Hart engines and Pirelli tires. The result was the highly successful TG280 with which Brian Henton and Derek Warwick finished 1-2 in the European Formula 2 Championship.Toleman decided to enter F1 and Byrne designed the less-than-successful TG81. With more experience the cars became much better and by 1984 Toleman was an established team, running Ayrton Senna in his debut season in F1. In 1986 the team was bought by the Benetton Group and was accordingly renamed Benetton Formula. That same year Gerhard Berger gave the team its first win in Mexico City.Byrne left Benetton in October 1989 to join the fledgling Reynard Formula 1 effort but, when Adrian Reynard decided to call off the program in September 1991, Byrne returned to Benetton as chief designer. His return to Benetton coincided with the arrival of Michael Schumacher and the combination led to Schumacher's controversial World Championship victory in 1994.When Schumacher left Benetton at the end of 1995 Byrne came close to retiring from Grand Prix racing, intending to spend his time in Thailand, indulging his passion for scuba-diving, but Schumacher campaigned to get Byrne to Maranello and he join Ferrari at the end of 1996. He led the design team which took Ferrari back to the top in Formula 1 in the glorious period between 1999 and 2002.