The 1965 Giro d'Italia was the 48th running of the Giro d'Italia, one of cycling's Grand Tour races. The Giro started in San Marino, on 15 May, with a 295 km (183.3 mi) stage and concluded in Florence, on 6 June, with a 136 km (84.5 mi) leg. A total of 100 riders from 10 teams entered the 22-stage race, which was won by Italian Vittorio Adorni of the Salvarani team. The second and third places were taken by Italian riders Italo Zilioli and Felice Gimondi, respectively.

The Giro d'Italia is an annual multiple-stage bicycle race primarily held in Italy, while also starting in, or passing through, other countries. The first race was organized in 1909 to increase sales of the newspaper La Gazzetta dello Sport, and the race is still run by a subsidiary of that paper's owner. The race has been held annually since its first edition in 1909, except during the two world wars. As the Giro gained prominence and popularity the race was lengthened, and the peloton expanded from primarily Italian participation to riders from all over the world. The Giro is a UCI World Tour event, which means that the teams that compete in the race are mostly UCI WorldTeams, with some additional teams invited as 'wild cards'.