In an extraordinary race, fitting for the 150th anniversary of the Cup itself, the six-year-old sped past favourite So You think to win by over two lengths.
French jockey Gerald Mosse said the win was special but the ride was easy.
"The job is so easy when we have the best race and the best horse," Mosse said.
New Zealand entry, Maluckyday, winner of the 2500m Lexus Stakes, came in second just pipping the Bart Cummings trained winner of the Caulfield Cup, So You Think, which came in third.
Americain, winner of this year's Geelong Cup, is trained by French trainer, Alain De Royer-Dupre, and is jointly owned by Australians, Jayco boss Gerry Ryan, and businessman Kevin Bamford.
Americain is only the second horse after Media Puzzle (2002) that has won the Geelong-Melbourne Cup double in the same year.
