She has been showing off her dark side recently, having swapped her signature peroxide locks for a brunette mane.
And Sarah Harding followed the same theme for her engagement party.
The singer looked glamorously gothic in a full-length black gown embellished with black, satin roses, embodying the femme fatale.
The Girls Aloud star was toasting her engagement to fiancé Tom Crane, the details of which she revealed exclusively to this week's HELLO!
And the couple were joined by her fellow bandmates Kimberley Walsh and Nicola Roberts at the exclusive Brompton Club in London.
Kimberley also opted for floor-length black and teamed it with a Chanel quilted bag.
Meanwhile, fashion week favourite Nicola – who arrived hand-in-hand with boyfriend Charlie Fennell - showed off her style in a brown lace Vivienne Westwood dress.
Cheryl Cole, however, did not attend the event as she is still recording in LA and presumably waiting to hear about her fate on the US X Factor judging panel.
Supermodel Rosie Huntington-Whiteley also made an appearance, again sporting black and accompanied by movie star boyfriend Jason Statham.
Despite several crates of champagne being spotted arriving at the South Kensington venue, the affair was low-key and the guests left looking fresh-faced.
Sarah's new dark and mysterious image fits with her plans for her wedding day.
She has revealed the theme will be gothic to pay tribute to her new favourite film Black Swan.
Sarah, 29, and DJ Tom Crane, 31, have been together for almost five years and became engaged on New Year's Eve on holiday in the Maldives.
Read a preview of the exclusive interview with HELLO!