The real singer of YouTube hit Gangnam Style took to Twitter to expose the imposter after spotting a picture of him posing with Justin Bieber's manager Scooter Braun.
PSY tweeted: "Seems like there's another ME at cannes...say Hi to him #PSYinSINGAPORE"
The fake PSY managed to blag his way into a series of VIP events at the glamorous festival and was lavished with gifts of free jewellery and champagne.
Stars, including Adrien Brody and James Bond actress Naomie Harris, flocked to meet him and posted pictures of themselves with him on Twitter.
The 'Skyfall' actress tweeted a photo with the doppelganger:
Naomie later tweeted: "It looks as if we've been fooled, that wasn't the real (PSY])! Could anyone else tell from the picture? Or am I just going crazy!? Haha!"
The imposter danced Gangnam Style on a French TV show and even signed a deal to take part in a Monaco gala.
According to the New York Post he was surrounded by three suited security guards wearing ear pieces at all times, which helped to convince people he was the real deal.