The 1959 Giro d'Italia was the 42nd running of the Giro d'Italia, one of cycling's Grand Tour races. The Giro started in Milan, on 16 May, with a 135 km (83.9 mi) stage and concluded back in Milan, on 7 June, with a 220 km (136.7 mi) leg. A total of 120 riders from 15 teams entered the 20-stage race, which was won by Luxembourgian Charly Gaul of the EMI team. The second and third places were taken by Frenchman Jacques Anquetil and Italian Diego Ronchini, respectively.

In road bicycle racing, a Grand Tour is one of the three major European professional cycling stage races: Giro d'Italia, Tour de France, and Vuelta a España. Collectively they are termed the Grand Tours, and all three races are similar in format, being three-week races with daily stages. They have a special status in the UCI regulations: more points for the UCI World Tour are distributed in Grand Tours than in other races, and they are the only stage races allowed to last longer than 14 days, and these differ from major stage races more than one week in duration.