Rosberg had a relatively late start to his F1 career, debuting at the age of 29 after stints in Formula Vee, Formula Atlantic and its antipodean counterpart Formula Pacific and Formula Two, then "feeder" series to Formula One. His first Formula One drive was with the Theodore team during the 1978 season. He immediately caught the attention of the Formula One paddock with a superb drive in the non-Championship BRDC International Trophy at Silverstone in just his second race with the team, emerging victorious after many of the big names had been caught out by a tremendous downpour. Rosberg wasn't able to qualify for a race afterwards, and was signed by another uncompetitive team, ATS, for three races after the Theodore team scrapped its unreliable car design. He returned to Theodore after they acquired chassis from the Wolf Formula One team, but these were also uncompetitive and Rosberg returned to ATS to end the season.
He next emerged with the Wolf team, midway through the 1979 season. However, the team was having difficulty staying solvent, and Rosberg had problems in finishing races. Rosberg soon had to change teams again when Wolf left Formula One, and signed with Fittipaldi Automotive which had bought the remains of Walter Wolf's squad. He secured his first two point-scoring results in the 1980 season, including a podium, but often failed to finish or qualify. 1981 was worse as he failed to score at all.
Despite this, Williams was interested in Rosberg, with the retirement of former World Champion Alan Jones leaving a seat open for the 1982 season. Given a competitive car, Rosberg had a highly successful year. He consistently scored points and earned his first victory in the Swiss Grand Prix at Dijon-Prenois late that year (despite being called the "Swiss Grand Prix", the race was held in France due to Switzerland's ban on motor racing in effect since the 1955 Le Mans disaster).
Rosberg's first memorable season came in a year where no driver won more than two races. With Ferrari's season marred by the death of Gilles Villeneuve at Zolder, the career-ending injuries to Didier Pironi at Hockenheim and the turbocharged Brabham-BMW and Renault cars suffering from poor reliability (and not helped by Brabham continually changing between the Ford V8 and the BMW turbo), consistency won Rosberg the Drivers' Championship, despite his Williams FW07C using the normally aspirated Ford DFY V8 engine which was considered outdated and out-matched against the vastly more powerful turbo cars. Rosberg's 1982 Championship proved to be the last World Championship win for the old Cosworth DFV engine which had been introduced to F1 by Lotus in 1967 (the DFY was a development of the DFV).
Rosberg's post-championship years would be hamstrung by both uncompetitive chassis from Williams, and the powerful but unreliable Honda turbo engine. For his title defense in 1983, Rosberg was again using the reliable Ford DFY V8. However, by this time, Ferrari, Renault and BMW had got their act together and the reliability of their turbo engines was starting to match their speed and power output. Rosberg still put his Williams FW08 on pole for the opening race of the season in Brazil (where he was disqualified from 2nd place because he was push started in the pits after he was forced to abandon his car in his pit bay due to a fuel vapor fire), and then won both the non-championship Race of Champions at Brands Hatch and in Monaco thanks to a clever choice of slicks at the start when all others started on wets, but it was increasingly obvious that without a turbo charged engine, results would be scarce. To that end, Frank Williams concluded a deal to run the Honda V6 turbo engine in his cars. Honda had come back into Formula One that year with the Spirit team and results had been slow with unreliability, but they were enthusiastic about joining Williams who had a reputation as a Championship-winning team. Rosberg and team mate Jacques Laffite first got their Honda turbos in the season ending South African Grand Prix at Kyalami and immediately the new Williams FW09 was on the pace. Rosberg finished in 5th place to give him 5th place in the championship. During the year, Rosberg earned the title "King of the atmospherics".
Despite good power from the Honda engines, Williams and Rosberg struggled in 1984 mostly due to the FW09B chassis not being rigid enough to handle the power delivery of the 850 bhp (634 kW; 862 PS) V6. The Finn managed to tame both the car and engine long enough to win the Dallas Grand Prix, but his only other podium for the year was a second at the season opener in Brazil (the 3rd time in succession he finished second in Brazil, but the only one from which he was not disqualified). After a frustrating year he finished the championship in 8th place with 20.5 points.
1985 would prove better for both Rosberg and Williams. The Finn had a new team mate in Nigel Mansell and the all carbon fibre Williams FW10 chassis was a big improvement over the FW09B. For the first few races the team used the 1984 engines until Honda introduced an upgraded version which improved power delivery, fuel economy and most importantly, reliability. Rosberg used the new engine to good effect, winning the Detroit Grand Prix and claiming pole in the next two races in France at the Paul Ricard Circuit and the British Grand Prix at Silverstone. Rosberg's pole-winning lap at Silverstone created history when he lapped the 4.719 km (2.932 mi) circuit in 1:05.591 for an average speed of 160.9 miles per hour (258.9 km/h). This would remain the single fastest lap of a circuit in Formula One until broken by Williams driver Juan Pablo Montoya at the 2002 Italian Grand Prix at Monza.
Keke Rosberg's fifth and final Grand Prix victory came at the 1985 Australian Grand Prix on the Adelaide Street Circuit. As it was the final race of the season, it was also Rosberg's final race for Williams. The win enhanced Rosberg's reputation as a "street fighter" as his final four wins (Monaco, Dallas, Detroit and Adelaide) had all come on street circuits.
Just as the Honda engine began producing regular results, Rosberg decided to leave Williams at the end of 1985 and signed for McLaren, winners of the 1984 and 1985 Drivers' and Constructors Championships. The Williams-Honda team would go on to dominate Grand Prix racing in 1986 and through 1987.
At the time, Rosberg's move to McLaren for the 1986 season had seemed a master stroke as they were the championship team of the previous two seasons, having done so (especially in 1984) in dominating fashion. However, the 1986 McLaren was now somewhat underpowered compared to its rivals, and Rosberg was soundly beaten by teammate, 1985 World Champion Alain Prost (the McLaren MP4/2C had been designed by John Barnard to suit the smoother style of Niki Lauda and Alain Prost, while Rosberg had never shed the ground effects style of late braking and throwing the car into a corner. It wasn't until it became known Barnard was leaving for Ferrari that the designer allowed Rosberg to fundamentally change his cars set up to suit his style. Ironically this coincided with Rosberg's only pole position of the season in Germany). On top of that, the fatal crash of Elio de Angelis while testing a Brabham in France deeply affected him (Rosberg and de Angelis were close friends) and he retired at the end of the season. He would later claim that he retired "too soon".
Keke Rosberg dominated the final race of his Formula One career, the 1986 Australian Grand Prix, though he did not win. While holding a 30 second lead over Nelson Piquet (his replacement at Williams), he had a rear tyre let go on lap 62. Thinking the noise from the back of his McLaren was engine related, he shut the engine off and pulled off the circuit, only to find when he got out and checked that all he needed to do was drive back to the pits to change tyres. However, he later revealed that he would never have won anyway, that he planned to give best to Alain Prost in the Frenchman's bid for back-to-back World Championships (Prost needed to win the race with Nigel Mansell finishing no better than 4th to claim the championship, while Rosberg had dropped out of title contention some races before). As it turned out, Prost won the race and the title, and a lap after Rosberg's retirement Mansell suffered the same fate as his former team mate, though in much more spectacular fashion.
Rosberg, who had made up his mind in mid 1984 that he would only race for two more years (but didn't announce it publicly until Germany 1986), had no regrets about leaving Williams and joining McLaren at a time when the Honda engine was starting to come on strong, while the Porsche built TAG engine (and the 3 season old MP4/2) was starting to show its age. In an interview following his retirement announcement, Rosberg said that he was glad he left Williams when he did, stating that had he stayed with them he may have quit Formula One early in the 1986 season after Frank Williams pre-season accident (in which he suffered a spinal cord injury which left him a tetraplegic) had left someone in a position of authority within the team who he said was one of the reasons he had decided to leave Williams, adding "We simply could not stand each other". While Rosberg did not name the person, it was generally believed to be Williams head designer and Technical Director Patrick Head, who had taken over the day-to-day running of the team while Frank Williams recovered from his accident.
