The campaign includes a series of photographs focused on the theme of "ready to race" to promote the five Harvey Nichols Ladies' Evenings at Haydock Park this summer.
The collection of pictures will appear in newspapers, online, magazine ads and promotional literature.
They include shots of Cumani, the daughter of eminent trainer Luca Cumani, posing in a black dress next to jockey mannequins and walking along the race track, while Spencer poses within a crowd of people with binoculars and holding a champagne bottle and glasses.
Harvey Nichols will also offer fashion shows, tips on beauty and general lifestyle workshops at the evenings.
Spencer said: "Fashion is part of the genetics of racing and it's great to see an innovative approach to adding value to the race goers' experience."
Dickon White, managing director of Haydock Park, said: "Jamie is a fantastic ambassador in the racing world and we acknowledge his sporting talents to be of the highest calibre.
"Together with Francesca we have a great marketing platform to broaden the appeal of racing to new and existing race goers."
The Harvey Nichols ladies' evenings will take place on May 23 and 30, July 4, August 1 and 8.