The British model and actress was seen with the 48-year-old 'Mr. Selfridge' star at his home in Malibu, California as well as at a fancy dress party in LA, according to reports.
Jeremy, who also stars in the US series 'Entourage' has previously been linked to singer Pink and burlesque star Dita von Teese.
Kelly, 33, split from rugby player Danny in August after he was caught sexting another woman.
According to The Mirror, Kelly was also spotted leaving Gethin's apartment, where he has been living whilst trying to find US TV work.
A source told the paper: “They have fancied each other for ages but have never been single at the same time before. Kelly thinks Gethin could definitely be boyfriend material."
“Gethin thinks Kelly is gorgeous. He can’t believe his luck, and he’d like this to become more serious," another insider added.