X Factor debut as a guest performer during last night's results show - ditching her usual preference of colour-clashing catsuits and skimpy leotards, in favour of a striking floor-sweeping gown.
Going glam: Jessie J showed off the results of her style makeover on ITV last night. Photo:Rex Features
The singer hit the stage to perform new single Who You Are, looking unusually elegant in the goth-glamlace-front gown - which was by relatively unknown Latvian designer, KatyaKatya Shehurina.
Jessie J joined former X Factor finalist Olly Murs in keeping the crowds entertained while the remaining five contestants awaited the verdict from this week's public vote.
How do you rate Jessie's glam makeover? Vote below:
See all the X Factor fashion from the judges and contestants here: