Sitting in fourth after the short programme on Wednesday when Massot doubled a triple jump, the duo skated a flawless free skate, beating their own world record mark in the process, and fell to the ice in tears after finishing.
Silver went to China's reigning World Champions Sui Wenjing and Han Cong and bronze to Canada's Meagan Duhamel and Eric Radford.
Double Olympic champion Hanyu to miss worlds
07/03/2018 AT 09:00
Russian pair Evgenia Tarasova and Vladimir Morozov had been tipped as strong favourites to win the event, but a fall in their final routine ultimately cost them as they finished in fourth place.