The 'Mascarathon', which takes place from 15-29 June, will feature Benefit staff, clients and customers as well as celebrities.
Participants will take one or more of the route's six legs - which include stop-offs in Newcastle, Cardiff, Birmingham and Oxford - all of which will incorporate Benefit parties.
"The event will celebrate the success of our best-selling mascara line, They're Real, and we're proud to help a worthy cause with hundreds of our staff taking part," said Benefit head of promotions Kyra Oates. "The event, and the parties along the way, were organised by our internal events team."
Benefit has previously worked with The Tailor of Shoreditch to create its presence at Clothes Show Live.