The 1973 Belmont Stakes was the 105th running of the Belmont Stakes at Belmont Park in Elmont, New York, held on June 9, 1973. Facing a field of five horses, Secretariat won by 31 lengths, the largest margin of victory in Belmont history, in front of a crowd of 69,138 spectators. His winning time of 2 minutes and 24 seconds still stands as the American record for a mile and a half on dirt. The event was televised and broadcast over the radio.

The Belmont Stakes is an American Grade I stakes race for three-year-old Thoroughbreds run at Belmont Park in Elmont, New York. It is run over the worldwide classic distance of 1+1⁄2 miles. Colts and geldings carry a weight of 126 pounds (57 kg); fillies carry 121 pounds (55 kg). The race, nicknamed The Test of the Champion, The Test of Champions and The Run for the Carnations, is the traditional third and final leg of the Triple Crown. It is usually held on the first or second Saturday in June, five weeks after the Kentucky Derby and three weeks after the Preakness Stakes. The 1973 Belmont Stakes and Triple Crown winner Secretariat holds the track record of 2:24.