The Breeders' Cup World Championships is an annual series of Grade I Thoroughbred horse races, operated by Breeders' Cup Limited, a company formed in 1982. From its inception in 1984 through 2006, it was a single-day event; starting in 2007, it expanded to two days. All sites have been in the United States, except in 1996, when the races were at the Woodbine Racetrack in Canada.

The attendance at the Breeders' Cup varies. Santa Anita Park set the highest two-day attendance figure of 118,484 in 2016. The lowest two-day attendance was 65,232 in 2025 at Del Mar Thoroughbred Club, aside from the years 2020 and 2021 when the Covic pandemic restricted events in public.

With the addition of three races for 2008, a total of $25.5 million was awarded over the two days, up from $23 million in 2007. With the subsequent removal of two races, the purses for the remaining thirteen races totaled $24.5 million in 2014, plus awards for foal and stallion nominators. Prior to the 2016 running, the total purses were raised from $26 million to $28 million. The purse of the Classic was raised from $5 million to $6 million, and the purse of the Longines Turf was increased from $3 million to $4 million. In 2018, total prizes and awards were increased to over $30 million after another race, the Juvenile Turf Sprint, was added and the purse for the Sprint was increased to $2 million.

Each Breeders' Cup race presents four Breeders' Cup trophies to the connections of the winner and a garland of flowers draped over the withers of the winning horse. Many Breeders' Cup winners will go on to win the Eclipse Award in their respective division. For example, of the eleven flat racehorse categories, seven of the Eclipse winners in 2015 had also won a Breeders' Cup race, while three others were in the money.

In the 2015 listing of the International Federation of Horseracing Authorities (IFHA), three Breeders' Cup races are ranked among the top Grade 1 races in the world: the Classic (4th), the Turf (10th) and the Mile (12th). The Distaff is ranked second among the top Grade 1 races for fillies and mares.

The event was created as a year-end championship for North American Thoroughbred racing, and also attracts top horses from other parts of the world, especially Europe. The idea for the Breeders' Cup was proposed at the 1982 awards luncheon for the Kentucky Derby Festival by pet food heir John R. Gaines (1928–2005), a leading Thoroughbred owner and breeder who wanted to clean up the sport's image. The Cup was initially faced with much skepticism in the racing community, but with the vocal support of legendary trainer John Nerud and others, the Breeders' Cup was carried out, and subsequently experienced tremendous popularity domestically and abroad.

The prize money is largely supported by nomination fees paid by breeders for stallions and the resultant foals. In North America, participating stud farms pay an annual nomination fee for a given stallions that is equal to the stallion's advertised stud fee, plus an additional amount if the stallion has more than 50 foals in a given year. The cost to nominate a European stallion is 50% of their stud fee, while the nomination fee for a South American stallion is 25% of their stud fee. In North America, the breeders of the resultant foals must also pay a one-time nomination fee (currently $400) by October 15 of the year of birth.

The races are operated by Breeders' Cup Limited, a company formed in 1982. The first event was in 1984. From its inception in 1984 through 2006, it was a single-day event; starting in 2007, it expanded to two days. All sites have been in the United States, except in 1996, when the races were at the Woodbine Racetrack in Canada.