The men's 400 metre freestyle competition of the swimming events at the 2023 Pan American Games were held on October 22, 2023, at the Aquatic Center in Santiago, Chile.

[1] Prior to this competition, the existing world and Pan American Games records were as follows: The first round was held on October 22.

[2] The B final was also held on October 22.

[3] The A final was also held on October 22.

[3]