Born in Stockholm in 1930, Bonnier came from a prominent and wealthy Swedish family whose members were heavily involved in the publishing industry — the family controlled the Bonnier Group. His father, Gert, was a professor of genetics. Bonnier spoke six languages, attended Oxford University for a year to study languages, and spent time in Paris before returning to Sweden. He began competitive racing at the age of 17 on a Harley-Davidson motorcycle and later competed in rallies before moving to circuit racing.
Bonnier entered Formula One in 1956 in a Maserati, and his first season included a serious accident at Imola in which his car was launched into the air after another driver cut across his path. His Maserati struck a large rock and catapulted, leaving Bonnier with concussion, cracked ribs, and a broken vertebra. He continued nonetheless.
His greatest Formula One achievement came at the 1959 Dutch Grand Prix at Zandvoort, where he drove a BRM to victory — the notoriously unreliable car having run cleanly while rivals Dan Gurney and Hans Herrmann were eliminated by brake failures. It was the first Formula One World Championship victory by a Swedish driver. He also won the 1960 German Grand Prix driving a Porsche 718 in a race held to Formula Two regulations as a transitional event ahead of the 1961 rule change.
Despite these wins, Bonnier's Formula One career was largely conducted with private or semi-private teams. He drove for BRM and Porsche as works entries, but after Porsche withdrew from Grand Prix racing at the end of 1962, he moved to Rob Walker Racing Team, driving Coopers and Brabhams, before establishing his own operation — initially called Anglo-Suisse Racing Team, later renamed Ecurie Bonnier — in 1966. His last full Formula One season was 1968, though he made occasional appearances until 1971.
Bonnier's sports car record was more consistently distinguished than his Formula One results. He won the Targa Florio twice: in 1960 co-driving a works Porsche 718 with Hans Herrmann, and again in 1963 with Carlo Mario Abate in another Porsche. In 1962 he shared a Ferrari 250 TRI entered by Count Giovanni Volpi with Lucien Bianchi to win the 12 Hours of Sebring.
His best Le Mans result came in 1964 when, co-driving a Ferrari 330P with Graham Hill for Maranello Concessionaires, he finished second overall. The same pairing won at Montlhéry that year, and a Ferrari 250LM gave Bonnier a further victory in a 12-hour race at Reims.
In 1966, Bonnier and Phil Hill won the 1000 km Nürburgring in a Chaparral — his last victory in a major sports car event. He continued racing in smaller events for years afterward, including a win at the 4 Hours of Le Mans in 1972 just months before his death.
Bonnier also participated in the 1968 Can-Am season, running a McLaren M6B. He had the pole position at the Karlskoga round but finished second, and his best Can-Am result was eighth at Las Vegas. In 1970, he drove a Lola T210 to the European 2-Litre Sports Car Championship drivers' title.
Alongside his racing activities, Bonnier was one of the driving forces behind the Grand Prix Drivers' Association, an organisation created to advocate for improved safety conditions in Formula One during an era when fatalities were common. He served as the Association's chairman until his death.
Bonnier was killed during the 1972 24 Hours of Le Mans. On the straight between Mulsanne Corner and Indianapolis, his Lola T280-Cosworth collided with a Ferrari Daytona driven by Swiss amateur Florian Vetsch. Bonnier's car was catapulted over the Armco barriers and into the trees alongside the track, and he was killed instantly. Vic Elford, who had stopped to assist Vetsch from his burning Ferrari, described seeing Bonnier's Lola spinning through the air like a helicopter.
Bonnier occupies a specific place in Formula One history as Sweden's first Grand Prix winner, a distinction that preceded the careers of Ronnie Peterson and Gunnar Nilsson by more than a decade. His role in founding and leading the Grand Prix Drivers' Association represented a serious contribution to driver safety advocacy at a time when the sport's attitude toward such concerns was largely indifferent. As a sports car racer, his Targa Florio and Sebring victories placed him among the competitive elite of the late 1950s and 1960s endurance scene.