BUENOS AIRES — After facing a wide backlash, the International Olympic Committee restored wrestling — one of the most traditional and elemental sports — to the Summer Games on Sunday.

Chastened by calls to modernize its leadership and energize its matches, wrestling changed its rules, created more weight classes for women and easily prevailed over squash and a combined bid by baseball and softball.

Wrestling received 49 votes, compared with 24 for baseball/softball and 22 for squash in voting by delegates of the Olympic committee. The vote, which was to add one of the three sports, guaranteed that freestyle and Greco-Roman wrestling would be contested at least through the 2020 Summer Games in Tokyo and the 2024 Olympics, which have yet to be awarded.

Last February, in what was seen as a wake-up call, the 15-member executive board of the I.O.C. removed wrestling from the core sports of the Summer Games after the 2016 Rio Olympics. The move drew heavy criticism because wrestling has been an integral Olympic sport.