The 1909 Giro d'Italia was the 1st edition of the Giro d'Italia, organized and sponsored by the Italian major sport newspaper La Gazzetta dello Sport. The event began in Milan on 13 May with a 397 km (247 mi) first stage to Bologna, finishing back in Milan on 30 May after a final stage of 206 km (128 mi) and a total distance covered of 2,447.9 km (1,521 mi). The race was won by the Italian rider Luigi Ganna of the Atala team, with fellow Italians Carlo Galetti and Giovanni Rossignoli coming in second and third respectively.

Conceived by La Gazzetta to boost its circulation at the expense of its rival Corriere della Sera, the 1909 Giro was the first stage road race. Its eight stages, although relatively few compared to modern Grand Tours, were each much longer than those raced today. The event began with a long primarily flat stage that was won by Dario Beni. He lost the lead after the next stage to the eventual winner Luigi Ganna, who in turn lost it to Carlo Galetti after the mountainous third stage. Ganna regained the lead after the fourth stage and successfully defended it all the way to the finish in Milan, winning three stages en route. Atala won the team classification.