2009-10: Matt Finn skated for the Toronto Marlboros Midget AAA in the GTHL. He scored 22 goals with 35 assists for the Marlies. One of four Marlboro Midgets selected in the first round of the 2010 OHL Priority Draft, Finn was selected by Guelph Storm with the 12th overall pick.
2010-11: Finn skated in 60 games for the Storm in his first OHL season and played for gold medal-winning Ontario at the 2011 U17 World Hockey Challenge. On a Storm team that allowed more goals than it scored, Finn finished with an even plus/minus and scored 2 goals with 18 assists and 23 penalty minutes. In the first round playoff series with Saginaw he had 3 assists and was plus-3. In five games at the WHC, he scored 1 goal and had 4 penalty minutes.
2011-12: Finn was the leading scorer amongst defensemen for Guelph in his second OHL season. In 61 games he scored 10 goals with 37 assists and was minus-13 with 58 penalty minutes. In a heart-breaking series that saw the Storm win the first two games only to have Plymouth win four straight (including Game 6 in overtime), Finn had 2 assists and was minus-one with 10 penalty minutes. Finn was rated 16th amongst North American skaters in Central Scouting’s final rankings prior to the 2012 NHL Draft. Finn was chosen in the second round, 35th overall, of the 2012 NHL Draft by the Toronto Maple Leafs.
2012-13: A case of mononucleosis and a knee injury limited Finn to 41 games in his third season with the Guelph Storm. He scored 11 goals with 20 assists and was +2 with 24 penalty minutes. Guelph finished fourth in the Midwest Division and lost to Kitchener in a first round playoff series. Finn did not play in the series. In August he was invited to Team Canada’s camp for the 2014 World Junior Championship.
2013-14: Finn was the leading scorer amongst defensemen for OHL champion and Memorial Cup runner up Guelph in his fourth season of junior hockey. He scored 14 goals with 47 assists and had 42 penalty minutes with a team-leading +57 plus/minus in 66 regular season games. Guelph finished first in the Midwest Division with the OHL’s top record and defeated North Bay in the OHL Finals. Finn scored 5 goals with 9 assists and was +17 with 6 penalty minutes in 20 playoff games. The Storm won their first three games at the Memorial Cup before falling to Edmonton, 6-3 in the championship game. Finn was +5 with 4 assists and 4 penalty minutes in four games at the tournament. He signed a three-year, entry-level contract with the Maple Leafs in November 2013.
Finn is a heady player described as a solid all-round threat. He is a strong defensive player that can handle tough assignments and can read the developing play and react accordingly. Finn's offensive game has continued to evolve. He needs to continue to add physical elements to his game as he is currently a bit undersized for an NHL defenseman and his skating is a concern.
Finn was traded along with four other prospects by the Toronto Maple Leafs to the New York Islanders in exchange for Michael Grabner.