2007-08: Nathan Beaulieu was chosen in the fourth round, 68th overall, of the 2008 QMJHL Entry Draft by the Saint John Sea Dogs.
2008-09: In his QMJHL rookie season, Beaulieu played in 49 games for the Sea Dogs. He scored 2 goals and chipped in 8 assists for 10 points. Beaulieu played for Team Atlantic at the 2009 World Under-17 Hockey Challenge, notching 2 assists in 5 games.
2009-10: In 66 games for the Sea Dogs, Beaulieu scored 12 goals and added 33 assists for 45 points. In 21 playoff games, he scored 4 goals and added 12 assists for 16 points.
2010-11: Beaulieu was the leading scorer among defensemen for the Memorial Cup champion Saint John Sea Dogs (QMJHL). On a unit that included high round picks Simon Despres (PIT) and Eric Gelinas (NJ), Beaulieu had a team-high 45 points (12 goals, 33 assists) and was +44 with 52 PMs. Beaulieu scored 8 of his 12 goals on the power play. In 19 playoff games for the Sea Dogs he scored 4 goals with 17 assists and was +6 with 26 PMs. He had 1 goal with 2 assists in four Memorial Cup games. Beaulieu played for Team Orr at the 2011 CHL Home Hardware Top Prospects Game, scoring 1 goal in Orr's 7-1 win over Team Cherry.
2011-12: After his first NHL training camp and pre-season games, Beaulieu was returned to the QJMHL for his third season with the 2011 Memorial Cup Champion, Saint John Sea Dogs. He started the season off playing a much more defensive role and being a physical presence in all three zones of the ice. The offensively skilled defender scored 11 goals (four on the power play and one shorthanded) along with 41 assists and an excellent plus 41 rating while taking 100 PIMs (four fighting majors) in 53 QJMHL games. Beaulieu was selected to play for the QJMHL in the Subway Super Series against Team Russia where he was one of the better defenseman for the QJMHL in the two game series. Beaulieu made Team Canada as the seventh defenseman for the 2012 World Junior Championship Tournament and was expected to lead their power play unit. He struggled defensively with a minus one rating while taking 16 PIMs and contributing just one assist in six games. Beaulieu and his power-house Sea Dogs returned to the 2012 Memorial Cup to defend their championship after storming through their four QJMHL playoff series, winning 16 games and only losing one game in overtime to Chicoutimi. The smooth skating defender really showed his abilities at both ends of the rink by contributing 15 points (4 goals, 11 assists) and an impressive plus 27 rating in 17 playoff games.
2012-13: Beaulieu made his NHL debut on March 30th — skating in six games for the Canadiens as a 20-year-old — and was the second-leading scorer for Montreal's AHL affiliate in Hamilton in his first pro season. He had 2 assists and was +5, averaging 15:22 minutes of ice time, during his time with Montreal. Beaulieu scored 7 goals with 24 assists in 67 AHL games and was -8 with 63 penalty minutes.The Bulldogs missed the AHL playoffs after finishing last in the North Division.
As well as quarterback the play from the blue line, Beaulieu is a highly mobile defenseman, who carries the puck well and can make things happen on the rush. He is smart about limiting the amount of chances he takes. He is still developing physically. Beaulieu is equally adept shooting and distributing the puck.
Beaulieu projects into a top-three defenseman in the NHL within the next few years if his development continues on its present pace. He needs to show more urgency and physicality in the defensive zone to play at the NHL level. The offensively talented blueliner will continue his pro career at the AHL level in Hamilton for the start of the upcoming season but could see time as an injury replacement for the Canadiens if it should be required.