Of the 109 riders that began the Giro d'Italia on 10 May, 65 of them made it to the finish in Milan on 31 May. Riders were allowed to ride on their own or as a member of a team. There were seven teams that competed in the race: Bianchi-Pirelli, Ganna-Dunlop, Gloria-Hutchinson, Legnano-Hutchinson, Maino-Clément, Touring-Pirelli, and Olympia-Spiga.
There were 65 cyclists who had completed all fifteen 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.
^In 1931, there was no distinction in the rules between plain stages and mountain stages; the icons shown here indicate that the third, fourth, fifth, sixth, seventh, ninth, tenth, eleventh, and twelfth stages included major mountains.