Polen's family moved from Detroit to Denton, Texas, where he took up motorcycle road racing in 1977 as a privateer. A serious crash in mid-1982 caused him to stop racing, but friends persuaded him to return in late 1985. In 1986 he entered the newly created Suzuki GSXR National Cup Series. His success in the series over two years earned him $260,000 in contingency fees, more than any privateer rider had earned in the history of American motorcycle racing. His performance secured him a contract with the Yoshimura Suzuki racing team in 1988, with whom he became the first competitor to win both the AMA 750cc Superbike and 600cc Supersport titles in the same year.
In 1989, Polen competed for Yoshimura in Japan, winning both the Formula 1 and Formula 3 categories in the All Japan Road Race Championship — the first rider to capture both titles in a single season. Later that year, he accepted a one-time offer to race in the Japanese round of the Superbike World Championship and made a striking impression, winning Race 1 and finishing fourth in Race 2.
Polen joined Eraldo Ferracci's Fast By Ferracci Ducati team for the 1991 Superbike World Championship. The season was extraordinary in its completeness. Polen won 17 of the 24 races and finished 150 points ahead of his nearest rival, defending world champion Raymond Roche. He also set a championship record by winning six consecutive pole positions during the season, a record that stood for 18 years until Ben Spies broke it in 2009. In a single season he also recorded 13 fastest laps, another WSBK single-season record.
Polen successfully defended his world championship in 1992, making him the first repeat winner in the Superbike World Championship. He also finished third in the AMA Superbike national championship that year, demonstrating competitive range across different racing formats.
In 1993 Polen left WSBK to focus on the United States, winning the AMA Superbike national championship. For 1994 he joined the Castrol Honda team in WSBK to race the new RC45, on the condition that the team use Dunlop tyres. He departed the team abruptly in early 1995, though not before pairing with Aaron Slight to win the Suzuka 8 Hours endurance race for Honda.
Polen transitioned successfully into endurance racing. He teamed with Peter Goddard to win the 1997 FIM Endurance World Championship and then switched to Honda to win the 1998 FIM Endurance World Championship alongside Christian Lavieille. His total of 18 AMA pole positions was a championship record until Mat Mladin matched it in 2006.
After retiring from professional competition, Polen established a road racing school dedicated to helping motorcyclists develop their skills. He was inducted into the AMA Motorcycle Hall of Fame in 2011 in recognition of his racing achievements.
Doug Polen's 1991 WSBK season stands as one of the most dominant individual championship campaigns in the history of motorcycle road racing. Winning 17 of 24 races while outscoring his nearest rival by 150 points across a full season remains a benchmark of sustained excellence. His contributions to American motorcycle racing, Japanese club competition, and international endurance racing make him one of the most versatile American racers of his era.