Hilton, 33, and Upshaw, 28, met last week during DT Model Management's second anniversary party at Pump restaurant in West Hollywood, reported E!Online.
"He's so nice and sweet. He's also a little older so that's good for Paris," an onlooker said.
Upshaw has modeled for Ralph Lauren, Abercrombie and Fitch, Tom Tailor, Mr Porter, FitFlop and Esquire Spain.