The men's 400 metres T11 event at the 2020 Summer Paralympics in Tokyo, took place between 28 and 29 August 2021.

The T11 category is for athletes with a visual impairment.

A T11 athlete may be entirely without sight, or be able to perceive light, but have no ability to see the shape of a hand at any distance.

T11 athletes commonly run with guides.

Prior to the competition, the existing records were as follows:[1] Heat 1 took place on 28 August 2021, at 11:54:[2] Heat 2 took place on 28 August 2021, at 10:50:[3] Heat 3 took place on 28 August 2021, at 10:50:[4] The final took place on 29 August 2021, at 19:35:[5]