Hilton, 34, and Joe, 32, have apparently been seeing each other for a few months, reported Ace Showbiz.
"Both of them were said to be partying in Cannes and staying at the Carlton hotel," an onlooker said.
Hilton arrived at the 2013 Cannes Film Festival alongside then-boyfriend River Viiperi.
Fournier was in a relationship with "TOWIE" star Chloe Sims back in 2013, but they split up after only few months of dating.