The 2021 Giro d'Italia was the 104th edition of the Giro, a three-week Grand Tour cycling stage race. It started on 8 May and finished on 30 May. On 26 May 2019, the race organisers RCS Sport originally announced that the start of the 2021 Giro would be in Sicily, Italy. However, on 4 February 2021, RCS Sport announced that the race would instead start in Turin, with the rest of the race route being announced on 24 February 2021.

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'.