BMX started in the early 1970s when children began racing their bicycles on dirt tracks in southern California, drawing inspiration from the motocross superstars of the time. The size and availability of the Schwinn Sting-Ray and other wheelie bikes made them the natural bike of choice, since they were easily customized for better handling and performance. BMX racing was a phenomenon by the mid-1970s. Children were racing standard road bikes off-road, around purpose-built tracks in California. The 1972 motorcycle racing documentary On Any Sunday is generally credited with inspiring the movement nationally in the US; its opening scene shows kids riding their Sting-Rays off-road. By the middle of that decade the sport achieved critical mass, and manufacturers began creating bicycles designed especially for the sport.

George E. Esser founded the National Bicycle League as a non-profit bicycle motocross sanctioning organization in 1974. before they set up the NBL, George and his wife, Mary, sanctioned motorcycle races with the AMA (American Motocross Association). Their two sons, Greg and Brian, raced motorcycles, but also enjoyed riding and racing BMX with their friends. It was their sons’ interest, and there being no BMX organizations in the East, that prompted George to start the NBL in Florida.

By 1977, the American Bicycle Association (ABA) was organized as a national sanctioning body for the growing sport. In April 1981, the International BMX Federation was founded, and the first world championships were held in 1982. Since January 1993 BMX has been integrated into the Union Cycliste Internationale.

The sport of Bicycle Motocross - Freestyle BMX is now one of the staple events at the annual Summer X Games Extreme Sports competition and the ETNIES backyard jam, held largely on both coasts of the United States. The popularity of the sport has increased due to its relative ease and availability of places to ride and do tricks.

In 2003, the International Olympic Committee made BMX a full medal Olympic sport for 2008 Summer Olympic Games in Beijing, China, and Māris Štrombergs (male, for Latvia) and Anne-Caroline Chausson (female, for France) were crowned the first Olympic champions..

Many great BMX riders go on to other cycling sports like downhill such as Australian Olympian Jared Graves, former "golden child" Eric Carter, and youth BMX racer Aaron Gwin.