Brook's new role as the Ultimo girls sees her following in the footsteps of previous the brand's previous models Mel B, Helena Christensen, Rachel Hunter, Sarah Harding and Melinda Messenger.
The Kent-raised actress's new position is her first high-profile modelling job since turning 30 last November.
Having been voted the Sexiest Woman in the World by the readers of FHM magazine, it's no surprise her 32E-26-36 hourglass figure has been chosen for the new Ultimo Spring campaign.
Ultimo creator Michelle Mone OBE said: 'Kelly is a natural beauty and is effortlessly sexy, making her the perfect choice for Ultimo. She epitomises the Ultimo woman and looks incredible in our new designs.
Having been voted the Sexiest Woman in the World by the readers of FHM magazine, it's no surprise her 32E-26-36 hourglass figure has been chosen for the new Ultimo Spring campaign.
Ultimo creator Michelle Mone OBE said: 'Kelly is a natural beauty and is effortlessly sexy, making her the perfect choice for Ultimo. She epitomises the Ultimo woman and looks incredible in our new designs.