The Men's 400 metre freestyle S9 event at the 2016 Paralympic Games took place on 9 September 2016, at the Olympic Aquatics Stadium.

Two heats were held.

The swimmers with the eight fastest times advanced to the final.

10:42 9 September 2016:[1] 10:49 9 September 2016:[1] 19:41 9 September 2016:[2]