Dotchin was selected by the Tampa Bay Lightning in the sixth round (No. 161) of the 2012 NHL Draft after he had 19 points (three goals, 16 assists) in 64 games with Owen Sound of the Ontario Hockey League. He signed an entry-level contract with the Lightning on April 19, 2014.
Dotchin was acquired by Barrie of the OHL in a trade with Owen Sound on Jan. 10, 2013 and finished the season with 22 points (four goals, 18 assists) in 66 games between the two teams. In 2013-14, he finished second among defenseman on Barrie with 36 points (11 goals, 25 assists) in 63 games.