The DEC - an umbrella organisation for several major aid charities - wants toraisefundsfor people in need of food, shelter and medicines as a result of Israel's military action in the Gaza Strip.
And like other supermodels before her, she's becoming her own brand: Last year, she collaborated with Momofuku Milk Bar to launch Karlie's Kookies, a line of vegan treats sold toraisefundsfor children's charities.
Organisers of the festival, in its 31st year, hope the move will enable them to keep ticket prices unchanged and raise more fundsforcharities through profits.