The women's 400m freestyle S8 event at the 2012 Summer Paralympics took place at the London Aquatics Centre on 31 August.

There were two heats; the swimmers with the eight fastest times advanced to the final.

WR = World Record.

PR = Paralympic Record.

Official London 2012 Paralympics Results: Heats Archived 2012-09-13 at the Wayback Machine Official London 2012 Paralympics Results: Final Archived 2012-09-13 at the Wayback Machine