The 24-year-old aspiring singer was enjoying a night out in the capital with fellow finalists including Union J before leaving the club with the tanned brunette.
He later got irate with paparazzi as he got into his waiting car with the woman, who bore a passing resemblance to Tulisa Contostavlos and wore a black dress, fur coat and a pair of red platforms.
Arthur also bought the girl a red rose before they headed home together.
It was reported earlier today that X Factor finalists Chris Maloney, Jahmene Douglas, Union J and Arthur have already recorded their respective winner's singles.
See pictures from Sunday's live results show here: