The men's 100 metre butterfly competition of the swimming events at the 2019 Pan American Games was held on August 7, 2019 at the Villa Deportiva Nacional Videna cluster.

[1] Prior to this competition, the existing world and Pan American Games records were as follows: The first round was held on August 7.

[2][3][4][5] The B final was also held on August 7.

[6] The A final was also held on August 7.

[7]