2009-10: Marc-Olivier Roy played 42 games for the Saint-Eustache Vikings in his first season in Quebec midget AAA hockey. He scored 9 goals with 14 assists and had 6 penalty minutes. In six playoff games he scored 1 goal with 4 assists and had 2 penalty minutes. Roy was selected by the Montreal Juniors in the third round (49th overall) of the 2010 QMJHL Entry Draft.
2010-11: Roy played three QMJHL games with Montreal and was the second-leading scorer for Saint-Eustache in his second season with the Vikings. He had 1 assist and was -1 with the Juniors. Roy scored 22 goals with 25 assists in 38 games for the Vikings – with his 47 points trailing only Anthony DeLuca (53). Saint-Eustache reached the provincial semifinals and Roy was third amongst all scorers in the playoffs with 11 goals and 14 assists in 10 games.
2011-12: Roy skated in 63 games for the re-located and re-named Blainville-Boisbriand Armada in his first full QMJHL season. He scored 17 goals with 22 assists and was +26 with 29 penalty minutes. The Armada finished first in the West Division and reached the second round in the playoffs. Roy scored 6 goals with 8 assists and was +11 with 14 penalty minutes in 11 playoff games.
2012-13: Roy was the Armada's third-leading scorer in his second season as Blainville-Boisbriand again finished first in the West Division. He scored 29 goals with 38 assists and was +12 with 68 penalty minutes in 65 games. The Armada reached the playoff semifinals and Roy scored 6 goals with 13 assists, finishing +4 with 10 penalty minutes, in 15 playoff games. He was ranked 54th amongst North American skaters in Central Scouting's final rankings prior to the 2013 NHL Draft.
At 6’0 and 174 pounds Roy is not huge, but is known as a hard-working player that is willing to dig deep into tough areas of the ice and is not without offensive talent. Roy’s main strength is his skating ability, which will aid in making him a great two-way player as he can power through traffic in the neutral zone quite easily. His quick skating and desire to dig deep into the corners sometimes work to his detriment however, as he is sometimes caught out of position in his own end. He has a decent shot from the slot and is often a major contributor to the Armada’s powerplay unit.
Roy will play another season of junior hockey with the QMJHL Blainville Boisbriand Armada. He was the third-leading scorer in the 2012-13 season and will look to get more ice time in 2013-14 to further improve his offensive numbers.