The 1923 Giro d'Italia was the 11th edition of the Giro d'Italia, a Grand Tour organized and sponsored by the newspaper La Gazzetta dello Sport. The race began on 23 May in Milan with a stage that stretched to Turin, finishing back in Milan on 10 June after a stage and a total distance covered of . The race was won by the Italian rider Costante Girardengo of the Maino team. Second and third respectively were the Italian riders Giovanni Brunero and Bartolomeo Aymo.
This year saw the debutant Ottavio Bottecchia finish in 5th place overall, and the leading 'isolate' (rider without a team). Bottecchia caught the attention of French rider Henri Pélissier, who instigated his glorious Tour de France career.
Of the 96 or 97 riders that began the Giro d'Italia on 23 May, 38 of them made it to the finish in Milan on 10 June. Riders were allowed to ride on their own or as a member of a team. There were three teams that competed in the race: Atala, Legnano, and Maino.
The peloton was completely composed of Italians. The field featured two former Giro d'Italia champions in the 1919 Giro d'Italia winner Costante Girardengo and returning champion Giovanni Brunero. Other notable Italian riders that started the race included Bartolomeo Aymo, Ottavio Bottecchia, Angelo Gremo, and Giovanni Rossignoli.
In 1923, the best amateurs could ride as guests in a professional team, these riders were called 'fuoriclassi amatoriali'.
In the first stage, a group of eight riders with all the favourites distanced themselves 11 minutes from all other riders. Girardengo won the sprint, and became the first leader.
The second stage was won by Aymo, almost a minute ahead of his rivals. Aymo became the new leader.
In the third stage, Linotti and Girardengo crossed the finish line very close to each other, and the jury could not determine who had won; both were declared winner. Two days later, the Italian Cycling Federation declared Girardengo to be the winner of the stage.
Girardengo also won the fourth and fifth stages, both ending in a bunch sprint. Because Aymo finished in the bunch both times, he remained leader.
In the sixth stage, Girardengo escpaed with Brunero, and won the sprint. Aymo finished multiple minutes behind, and lost his lead; Girardengo became leader again.
In the following stages, Girardengo was dominant, winning all of them except the ninth stage where he was narrowly beaten by Sivocci in a sprint. Girardengo thus became the clear winner of the Giro, winning eight of ten stages.
There were 38 cyclists who had completed all ten stages. For these cyclists, the times they had needed in each stage was added up for the general classification. The cyclist with the least accumulated time was the winner. Ottavio Bottecchia won the prize for best ranked independent rider in the general classification.