The Canadiens avoided what would have been a season high-tying fourth straight loss in thrilling fashion.
Down 4-1 in the third period, they scored three time in the final 3:22, including David Desharnais' buzzer-beater.
On the game-winner, Max Pacioretty fired a shot from low in the right circle. Ottawa goalie Robin Lehner made the save and felt the puck was covered up. However, the referee didn't blow the play dead and Pacioretty dislodged the puck and Bouillon put it into the open net, snapping
P.K. Subban assisted on all three of Montreal's third-period goals, while Carey Price made 30 saves in his return to the Canadiens' crease.
It was Price's first action since helping Canada win its second straight gold medal at last month's Olympics. He missed Montreal's first eight games following the NHL's resumption of play with a lower-body injury he aggravated in Russia.