1780 in sports

1780 in sports describes the year's events in world sport.

Boxing
Events
 * It was probably during this year that Harry Sellers reclaimed the vacant English Championship but he is not known to have defended it before 1785.
 * Unknown date - A three-day horse racing event is held in Hempstead Plains on Long Island, USA. The event includes a women's class.

Cricket
Events England
 * Duke & Son of Penshurst made the first-ever six-seam cricket ball.
 * Most runs – Joseph Miller and James Aylward 142
 * Most wickets – Lumpy Stevens 18

Horse racing
Events England
 * Inaugural running of The Derby, sometimes called the Epsom Derby for differentiation purposes, on Epsom Downs. The third-oldest of the five British Classic Races, the race is named after its founder, the 12th Earl of Derby.
 * The Derby – Diomed
 * The Oaks – Tetotum
 * St Leger Stakes – Ruler