Braun entered Grand Prix motorcycle racing in 1968 and quickly established himself as a competitive force across multiple classes. His natural ability was evident in his approach to the Isle of Man TT, the sport's most demanding and technical circuit at the time. At 37.7 miles per lap, the Mountain Course typically requires competitors multiple attempts before they can learn its nuances and challenge for victory. Braun won at the TT on his first attempt in 1970 — a feat achieved by only seven riders in the event's history at that point.
The 1970 season proved to be Braun's breakthrough year. Riding for Suzuki, he won the 125 cc FIM World Championship, claiming a title that established him among the leading lightweight-class specialists in the sport. His Isle of Man TT victory that year was a highlight of the campaign.
Braun became unexpectedly entangled in Cold War politics after winning the East German Grand Prix during the 1971 season. During the victory ceremony, as the West German national anthem played, members of the East German crowd began singing the anthem's lyrics — an act of defiance that drew immediate official reaction. The East German government responded by restricting the following year's race to invited participants only, and by 1973 the race had been removed from the Grand Prix calendar entirely.
Three years after his 125 cc title, Braun added a second world championship to his record. Riding a Yamaha TZ 250, he won the 250 cc FIM World Championship in 1973, confirming his versatility across displacement classes and his sustained competitiveness at the highest level of the sport.
In addition to his two-wheel career, Braun participated in four-wheel motorsport. He entered five races with Team Warsteiner Eurorace in the 1975 European Formula Two Championship, demonstrating the breadth of his competitive instincts beyond his primary discipline.
Braun's racing career came to an end following a serious accident at the 1977 350 cc Austrian Grand Prix at the Salzburgring. The crash occurred after he had already withdrawn from the Grand Prix motorcycle racing world championship calendar following his last full seasons in the mid-1970s.
Dieter Braun's two world championships — claimed on machinery from different manufacturers across different displacement classes — place him among the more versatile champions of Grand Prix motorcycle racing's pre-modern era. His unexpected role in the East German Grand Prix controversy of 1971 gave his career a historical resonance beyond the circuits, illustrating how motorcycle racing in divided Europe could become entangled in the political tensions of the time. He remains one of West Germany's most decorated Grand Prix motorcycle racers.