The ex-Spice Girl appears in the advertising campaign for the beachwear collection for Next.
Halliwell told the Daily Mail: "It's about inspiring confidence with great looking swimwear for all body shapes."
She previously said of the range: "It's for real women of all shapes and sizes. Everything is mix and match, so you can choose the exact shapes and styles that suit you. This is a collection that makes you look good and feel fabulous."
Items will be on sale in stores and online from next month.
In 2008, Halliwell admitted that she felt "self-conscious" about stripping off in public and suggested that she may not be photographed in a bikini again.