The Melbourne-based star, who was recently crowned as the winner of this year's Australia's Next Top Model, said that the rumours of her dating Amazing Race winner Joliffe are completely unfounded.
Cox told the Herald Sun: "We just went out as friends and then there was a story saying we were in love."
However, onlookers at Surry Hills restaurant Toko last week claimed that Cox and Joliffe were "smiling a lot", adding: "It had to be a date."
Joliffe recently split from former Neighbours actress Erin McNaught after two years together.
Since their split, McNaught said: "I adore Nathan. We are still really close, but it was a matter of our lives conflicting. Our lives were slowly heading in different directions. So we decided to call it quits rather than go through that strain."
After being named Australia's Next Top Model, Cox said that she felt "incredible", but she was later forced to slam reports that she is too thin, saying: "I'm a very healthy girl and am always exercising. You do want to do the right thing and be a good role model for people, and not promote the idea that if you want to be a model, you have to be skinny and look the right way."