Piven was spotted leaving a nightclub here with the blonde model after spending a very cosy evening together, reported Contactmusic.
Hunter, 44, who previously dated Robbie Williams and was married to Rod Stewart for 16 years until 2006, later hinted on Twitter that she had a very romantic evening.
She tweeted a picture of a fox with the caption, "Fox and Full Moon...In London... Magic."
Piven, 48, has made himself at home in the UK since moving there to play department store tycoon Harry Selfridge in the ITV drama series 'Mr Selfridge'.