The men's 400 metre freestyle S12 event at the 2012 Paralympic Games took place on 30 August, at the London Aquatics Centre.

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

Sergey Punko won the gold medal in a time of 04:10.26.

It was Russia's first gold of the London 2012 Paralympics.

Official London 2012 Paralympics Results Archived 2012-08-30 at the Wayback Machine Final Result