Berger's father Johann owned a road haulage company in Austria, where Gerhard worked as a truck driver. A multiple race winner in European Formula Three, he joined the ATS team in Formula One for 1984. A week after that debut season ended, Berger survived a serious road accident near Salzburg in which his BMW was rammed from behind and cartwheeled off a cliff. He was thrown clear through the rear window — he was not wearing a seatbelt — and sustained a broken neck and damaged vertebrae. Two surgeons who happened upon the scene stabilised him and he made a full recovery.
A full season with Arrows followed in 1985, where both Berger and teammate Thierry Boutsen were hampered by the Arrows A8's inability to harness the BMW M12 engine's power.
Berger's career accelerated when he joined Benetton in 1986. He won his first Grand Prix at Mexico City, aided by a Pirelli tyre strategy and the exceptional power of the BMW turbo — he recorded the highest straight-line speed of the first turbo era, clocking 351.22 km/h at Monza during the 1986 Italian Grand Prix. He also competed for the German Schnitzer BMW team in the European Touring Car Championship, winning the 1985 Spa 24 Hours alongside Roberto Ravaglia and Marc Surer.
Berger signed for Ferrari in 1987 and won the final two races of the season — Japan and Australia — from pole position at both venues, Ferrari's first back-to-back victories since Gilles Villeneuve in 1981. He entered 1988 tipped as a championship favourite alongside Enzo Ferrari's death and McLaren-Honda's extraordinary dominance that year. Berger was the only driver to win a non-McLaren race in 1988, taking the Italian Grand Prix at Monza after Ayrton Senna became entangled with a backmarker; he was also the only non-McLaren driver to claim a pole position that year, at Silverstone.
In 1989, partnered by Nigel Mansell, Berger survived a terrifying crash at Tamburello during the San Marino Grand Prix, his Ferrari going into the wall at close to 180 mph before catching fire. It took sixteen seconds for rescue crews to reach the car. He missed only the Monaco Grand Prix and returned to score a win in Portugal, which was overshadowed by the Senna-Mansell pit-lane incident. Berger attributed his relatively minor injuries partly to the car's semi-automatic gearbox, which kept his hands on the wheel rather than the gearstick at the moment of impact.
From 1990 to 1992, Berger joined Ayrton Senna at McLaren. Their three years together produced some of the sport's most celebrated off-track stories: Berger filled Senna's bed with frogs, replaced Senna's passport photo with an obscene image that led to the Brazilian being detained in Argentina for twenty-four hours, and used a fire-hose extension to flood Senna's hotel room at three in the morning. Senna retaliated in kind, supergluing all of Berger's credit cards together.
On track, Berger out-qualified Senna on occasion but rarely matched the Brazilian's race pace. He won the 1992 Canadian Grand Prix and the 1992 Australian Grand Prix — McLaren's last race with Honda engines. The 1990 season brought no wins but Berger took pole position at the United States Grand Prix, beating Senna in qualifying.
Berger returned to Ferrari in 1993 alongside Jean Alesi. The 1993 car was uncompetitive and the active suspension unpredictable. A highlight of the season came at Monaco, where Berger attempted an audacious move on Damon Hill at the Loews hairpin while challenging for second position.
In 1994, following the deaths of Senna and Roland Ratzenberger at Imola, Berger delivered an emotional win for Ferrari at the German Grand Prix at Hockenheim — the team's first victory since the 1990 Spanish Grand Prix. He claimed pole again at Estoril and was leading the Portuguese Grand Prix before making an error that allowed Mansell through. He also led the final race of the season in Australia until a mistake handed the same result to Mansell.
Berger moved to Benetton for 1996 and 1997. The 1996 season was disappointing: he nearly won at Hockenheim before his engine failed. For 1997, after a three-race layoff for sinusitis surgery and the sudden death of his father Johann in a light aircraft accident, Berger returned to win at Hockenheim for the second time in his career — taking pole, victory, and fastest lap. It was Benetton's final Grand Prix win and came eleven years after his first win with the same team, the longest interval between first and last victories for any team in Formula One. He announced his retirement at the same event and concluded his career with a close fourth at Jerez in the final round.
After retiring, Berger held a senior role at BMW overseeing their return to Formula One as an engine supplier. In 2006 he acquired a fifty percent stake in Scuderia Toro Rosso from Red Bull, selling it back to Dietrich Mateschitz at the end of 2008 after Toro Rosso had won their first Grand Prix with Sebastian Vettel at Monza. Berger served as President of the FIA Single Seat Commission from 2012 to 2014 and became chairman of the Deutsche Tourenwagen Masters organisation in 2017.