The Belmont Stakes is an American Grade I stakes Thoroughbred horse race held every June at Belmont Park in Elmont, New York. The race is the third and final leg of the Triple Crown, following five weeks after the Kentucky Derby, and three weeks after the Preakness Stakes. The 2004 Belmont Stakes drew a massive television audience of 21.9 million viewers and had the highest household viewing rate since 1977 when Seattle Slew won the Triple Crown.

The Belmont Stakes is a 1.5-mile (2.4 km) horse race, open to three year old Thoroughbreds. Colts and geldings carry a weight of 126 pounds (57 kg); fillies carry 121 pounds (55 kg). The attendance at the Belmont Stakes ranks fourth in North America and usually surpasses the attendance of all other stakes races, including the Breeders' Cup. The attendance at the Belmont Stakes typically trails only the Kentucky Derby, the Preakness Stakes and the Kentucky Oaks. For more information, see American Thoroughbred Racing top Attended Events.

The first Belmont Stakes was held at Jerome Park Racetrack in The Bronx, built in 1866 by stock market speculator Leonard Jerome (1817–1891) and financed by August Belmont, Sr. (1816–1890), for whom the race was named. The race continued to be held at Jerome Park until 1890, when it was moved to the nearby facility, Morris Park Racecourse. The race remained there until the May 1905 opening of the new Belmont Park, 430-acre (1.7 km²) racetrack in Elmont, New York, on Long Island just outside the New York City borough of Queens.

When anti-gambling legislation was passed in New York State, Belmont Racetrack was closed, and the race was cancelled in 1911 and 1912.

The first post parade in the United States was at the 14th Belmont, in 1880. Before 1921, the race was run in the clockwise tradition of English racing. Since then, the race has been run in the American, or counter-clockwise, direction. The winner of the Belmont Stakes is presented the August Belmont Trophy, one of the most prestigious trophies in the country.

Because of its length (one lap around the enormous Belmont main track), and because it is the final race of the Triple Crown, it is called the "Test of the Champion". Most three-year-olds are unaccustomed to the distance, and lack the experience, if not the stamina, to maintain a winning speed for so long. In a long race such as the Belmont, positioning of the horse and the timing of the move to chase for the lead can be critical.

Due to the restoration and renovation of Belmont from 1963–1967, the race was held at Aqueduct Racetrack.