The pair's music, modelling and acting backgrounds and fresh new personalities are seen as making them an ideal extension to the contribution made by Kate as the brand's international profile grows.
"I have always had a passion for make-up, ever since I was a little girl and I am very attached to Rimmel as it was my first make-up brand," says singer Sophie, who's known for her alabaster skin and adventurous use of cosmetic colours.
Her fellow newly appointed brand ambassador, model and actress Lily, who's going to have to fit in her Rimmel commitments around the degree course she's going to embark upon at Cambridge, adds: "I am really looking forward to working with Rimmel London. Their products are young, glamorous and fun and have been a British staple of my make-up bag all my life."
Sophie and Lily are to appear in a number of campaigns during 2008, while Kate will continue to feature in her own advertising for Rimmel London.
"We believe our consumers will really identify with both new signings," says Stephen Mormoris, a senior vice president with the cosmetic house.