2009-10: Matej Paulovic skated in Slovakia's U18 league as a 14-year-old – playing for HC Topolcany. He scored 17 goals with 16 assists and was +13 with 26 penalty minutes in 39 games.
2010-11: Paulovic played two games with HC Nitra's U20 team and was the leading scorer for HC Topolcany's U18 team. He represented Slovakia at the U17 level in the 2011 World Hockey Challenge and 2011 Europe Youth Olympic Festival tournaments. He was +1 with no points nor penalty minutes for HC Nitra. Paulovic scored 33 goals with 29 assists and was +15 with 34 penalty minutes in 42 games for HC Topolcany U18. Playing for Slovakia, he had no points with 4 penalty minutes at the World Hockey Challenge and had 1 assist in three games at the EYOF.
2011-12: Paulovic joined Swedish club Farjestad, skating for the U20 and U18 teams, and played for Slovakia in the 2012 U18 World Junior Championship Division 1A tournament. He scored 2 goals with 1 assist and was -2 with 6 penalty minutes in 12 games in the U20 SuperElit League. Paulovic scored 17 goals with 23 assists in 33 regular season games for Farjestad's U18 team and was +34 with 51 penalty minutes. Farjestad avoided relegation to the second division after finishing seventh. Paulovic scored 2 goals with 1 assist and was -2 in six relegation playoff games. In five games for Slovakia's U18 team he scored 1 goal with 1 assist and was +4 with 6 penalty minutes. Slovakia swept the WJC D1A tournament to gain elevation to the top group for 2012-13.
2012-13: Paulovic split the season between the Farjestad U20 and U18 teams in his second season in Sweden. He scored 5 goals with 12 assists and was +8 with 6 assists in 34 U20 SuperElit league games. Farjestad finished fourth and reached the playoff semifinals, falling 5-3 to HV 71. Paulovic played in all seven playoff games, scoring 1 goal with 1 assist, and was +1 with 6 penalty minutes. In eight games with Farjestad's U18 team he scored 3 goals with 4 assists and was +4 with 8 penalty minutes. Not among the 130 European skaters in Central Scouting's final rankings, Paulovic was selected by Dallas in the fifth round (149th overall) of the 2013 NHL Draft. He was selected by Peterborough in the first round (eighth overall) of the 2013 CHL Import Draft.