The limited edition collection will be a tightly edited précis of Williams' debut a/w 2013 show, which was part of Fashion East.
Denim forms the cornerstone of Williams collection, where she revisited its roots in an exploration of vintage Americana.
Up for grabs will be eight pieces from the runway, recreated exclusively for Selfridges and featuring dancing cowgirls, fringing and horse head motifs.
It will also be the first opportunity to buy a/w 2014 Ashley Williams anywhere in the world, ahead of her mainline collection hitting stores in September.
It will be available exclusively at Selfridges from 14 August.