Cheryl Tweedy took to Instagram to share images from the campaign which sees her along with Nicola Roberts, Kimberley Walsh and Nadine Coyle sport matching blue pyjamas and nighties decorated in stars, with voluminous hair.
The pyjama sets retail for £18 each while the nightshirts cost £14 and will be available in all UK Primark stores.
Explaining the story behind the images, Tweedy captioned her post: “Before Sarah passed away, we promised her we would fulfil her wish of raising money for vital research to help determine young women between the ages of 29 and 40 who could be at risk of breast cancer with no genetic history.
“These pyjamas with @primark will raise a significant amount of money to help us achieve our promise to her. The PJ’s will be in all UK and ROI Primark stores from tomorrow.
“ALL proceeds raised will be split equally between The Christie Charitable Trust and Cancer Research UK. #BreastCancerAwarenessMonth.”
The news comes hot on the heels of Girls Aloud announcing that they will be hosting a fundraising gala for cancer research on October 8.
The Primrose Ball will be held at The Londoner hotel in central London with performances from the likes of Olly Alexander and a live auction which includes an original canvas depicting the pop star by artistic duo the Connor Brothers.
The charity gala will raise funds for the Christie NHS Foundation Trust and Cancer Research UK, as part of the Sarah Harding Breast Cancer Appeal.
Harding died aged 39 last September after revealing she had breast cancer which had spread to other parts of her body..