Belgian Prime Minister, Charles Michel and the US Ambassador to France, Jane Hartley, attended the ceremony, along with the head of the French rail firm, SNCF.
After he was wounded, Stone is also credited with assisting a French-American passenger who was wounded by a bullet.
Spencer Stone, 23, Alek Skarlatos, 22, and Anthony Sadler, 23, were presented with the Legion of Honor in Paris on Sunday.
A fourth man, British businessman Chris Norman, was also honored on Monday. A gunshot had awakened them, and a passenger, whom Hollande identified as Mark Moogalian, a 51-year-old French-American citizen, had been hit in the throat and was bleeding badly.
“I feel our training mostly kicked in after the assailant was already subdued”, said Skarlatos.
“He seemed like he was ready to fight to the end”, Stone said.
France had been on high alert since January when Islamist militants killed 17 people in and around Paris – including the attacks on the offices of the satirical paper, Charlie Hebdo.
Prosecutor Francois Molins says 26-year-old Moroccan suspect Ayoub El-Khazzani had used his phone to watch the YouTube video. They were “worthy of a frontline officer”, Le Monde newspaper said in praise of the Americans’ rejection of “inaction” and “passivity”.
The French Legion of Honor medal was a creation of Napoleon Bonaparte, and is usually reserved for those who have served France and the ideals for which it stands. They moved swiftly and heroically and may have saved the lives of scores of their fellow passengers.
“You averted what could have been a true carnage”, Mr Hollande said. During the struggle, El-Khazzani pulled out a handgun and box cutter, slicing Stone in the arms.
“His intentions were pretty clear”, said Skarlatos, a 22-year-old member of the National Guard in Oregon who was on holiday in Europe with his friends after he had recently returned from Afghanistan, adding the gunman “never said a word”.
“Hiding or sitting back is not going to accomplish anything ad the gunman would have been successful if my friend Spencer would not have gotten up”, said Sadler.
“A guy with an AK entered the train cabin, so me and my friend got down, and basically I said ‘let’s go, ‘” Skarlatos said, describing how they foiled the potentially deadly attack.
The gunman who opened fire on a train travelling from Amsterdam to Paris claimed he found the AK-47 assault rifle in a park by chance and planned to hold up the train, his former lawyer says.