Byrne grew up in Pretoria and developed an interest in motor racing while studying at Witwatersrand University in Johannesburg, initially as a competitor and later for the technical side of the sport. After graduating in 1964 he worked as a chemist, but by the late 1960s he had co-founded a performance car parts import company called Auto Drag and Speed Den with friends Dave Collier, Ronny, and Dougie Bennett, first on Jules Street in Malvern, Johannesburg, and later on Voortrekker Road in Alberton. Despite lacking formal engineering qualifications, Byrne applied his mathematical knowledge to designing racing cars. His first effort, a Formula Ford racer, was competitive and finished well in the 1972 championship.
That success prompted Byrne to relocate to England. He purchased an ageing Royale Formula Ford car and spent time refining his design skills before a lucky break in 1973: when Royale founder Bob King decided to sell the team, the new owner hired Byrne to replace King as designer. Byrne spent four years producing cars for Royale and its customers, establishing a reputation in British motor racing.
An introduction to Ted Toleman in 1977 opened the next chapter. Toleman ran a Formula Two team and engaged Byrne as its designer; the partnership culminated in first and second place in the 1980 European Formula Two Championship, signalling readiness for Formula One.
The first Byrne-designed Formula One car, the Hart-powered Toleman TG181, appeared at the 1981 San Marino Grand Prix — the team's opening championship round, after financial constraints had forced them to skip the three long-haul season-openers. Two seasons passed before Derek Warwick and Bruno Giacomelli collected ten points in 1983, enough for ninth in the Constructors' Championship and real credibility for Byrne in the pit lane. The following winter Toleman signed Ayrton Senna, and the combination came agonisingly close to winning the rain-shortened 1984 Monaco Grand Prix.
Progress accelerated when the Benetton family purchased Toleman in 1985, bringing greater resources and the turbocharged BMW M12 engine. By October 1986, Gerhard Berger had scored the first victory for a Byrne-designed car at the Mexican Grand Prix. Four further race wins followed over the next five seasons, though Benetton could not consistently challenge Ferrari, Williams, and McLaren.
After a brief spell on the abandoned Reynard Formula One project in 1991, Byrne returned to a Benetton now controlled by Flavio Briatore and driven by Michael Schumacher. The B193 introduced a semi-automatic gearbox, four-wheel steering, active suspension, and traction control, taking a single victory. The subsequent B194 was the dominant car of 1994, though the team was dogged by accusations of illegal electronic aids and a late-season Williams charge denied Byrne a first Constructors' title. In 1995, with those controversies behind them, Benetton secured both championships. Byrne announced his intention to retire when Schumacher left for Ferrari at the end of the year.
Schumacher's arrival at Ferrari brought a mandate to rebuild the team's engineering structure. Technical director Ross Brawn was recruited from Benetton, and Ferrari approached Byrne to succeed chief designer John Barnard, who declined to relocate to Italy. After extended negotiations, Byrne was drawn from his retirement in Thailand to establish a new design office at Ferrari's Maranello headquarters.
The impact was immediate: Ferrari took the title fight to the final race in both 1997 and 1998. In 1999 the team won the Constructors' Championship for the first time in seventeen years. By the end of 2004, Byrne-designed Ferraris had claimed 71 victories, six consecutive Constructors' titles, and five consecutive Drivers' titles for Schumacher — a level of sustained dominance unprecedented in the sport. Byrne announced in 2004 that he would step back from the chief designer role at the end of the 2006 season, handing over to Aldo Costa — his assistant since 1998 — though he remained at Ferrari as a consultant into early 2009.
Byrne was subsequently called back in technical advisory and mentoring roles on several occasions. He was involved in assessing the troubled Ferrari F2012 in 2012 and contributed to the design of the LaFerrari road car. In a February 2013 interview at the launch of the Ferrari F138, he stated he was working full steam on Ferrari's 2014 Formula One car. Team principal Maurizio Arrivabene later confirmed Byrne was serving as a mentor to chief designer Simone Resta. Byrne was heavily involved in the Ferrari F1-75 of 2022 — a car competitive enough to earn a contract extension — and its successors the SF-23 and SF-24. The SF-24 finished as runner-up in the 2024 Constructors' Championship, Ferrari's most competitive title challenge since 2012.
Byrne's guiding design motto — "Evolution not Revolution" — shaped a body of work defined by incremental, meticulous refinement rather than dramatic conceptual leaps. Working without formal engineering qualifications, he transformed self-taught mathematical instinct into machinery capable of record-breaking championship runs. His Ferrari cars of the early 2000s remain the benchmark for sustained dominance in Formula One's modern era.