2010-11: Nicholas Paul played for the Mississauga Senators minor midget AAA team in Ontario. He scored 14 goals with 11 assists and had 12 penalty minutes in 37 games. He played five games in the OHL Cup with the Senators and scored 2 goals with 2 assists.
2011-12: Paul played nine games in Canadian Junior A hockey with the Mississauga Chargers and played for the Mississauga Reps midget AAA team in the Greater Toronto Hockey League. He scored 3 goals with 2 assists and had 4 penalty minutes with the Chargers. Paul scored 1 goal with 3 assists in five games for the Reps at the Ottawa Senators Midget AAA showcase in October. Paul was the MVP of the GTHL's All-Star game and scored 14 goals with 8 assists in 38 games for the Reps. He was selected by Brampton in the fifth round (95th overall) of the 2012 OHL Priority Draft.
2012-13: Paul skated in 66 games for Brampton in his first OHL season. He scored 12 goals with 16 assists and was +6 with 21 penalty minutes. Brampton reached the playoffs, finishing second in the Central Division, but fell to third-place Sudbury in a first round playoff series. Paul had 1 assist and was -4 in the five-game series. He was ranked 124th amongst North American skaters in Central Scouting's final rankings and was selected by Dallas in the fourth round (101st overall) of the 2013 NHL Draft.