2009-10: J.T. Brown, son of former NHL running back Ted Brown, was the leading scorer for the Waterloo Black Hawks in his second season in the USHL. He scored 34 goals with 43 assists and was plus-37 with 64 penalty minutes in 60 games. Waterloo finished fourth in the East Conference and faced the eventual Clark Cup champion Green Bay Gamblers in the playoffs. Brown had 1 goal and was minus-two in the three-game series. Brown committed to playing college hockey at Minnesota-Duluth in 2010-11.
2010-11: Brown stepped into a key role for NCAA national champion Minnesota-Duluth as a freshman; skating in all 42 games and finishing as the Bulldogs' fourth-leading scorer. Brown scored 16 goals with 21 assists and was plus-six with 50 penalty minutes while skating primarily on the Bulldogs' second line with Travis Oleksuk and Kyle Schmidt. The Bulldogs finished fourth in the WCHA and after an upset loss to Bemidji State in the WCHA tournament won four straight NCAA tournament games to capture the title. Brown was named the Frozen Four MVP and selected for the WCHA's All-Rookie Team.
2011-12: Brown made his NHL debut — skating in five games with Tampa Bay after signing a two-year entry-level contract with the Lighting in March 2012 — following his sophomore season at Minnesota-Duluth. Brown had 1 assist and was plus-two, averaging just under 14 minutes of ice time, in his stint with the Lightning. Brown was the third-leading scorer for the Bulldogs; scoring 24 goals with 23 assists in 39 games and finishing plus-29 with 59 penalty minutes. Minnesota-Duluth finished second in the WCHA and earned an NCAA at-large bid after reaching the WCHA tournament semifinals. Brown represented the USA in the 2012 U20 World Junior Championship and was plus-four with 1 goal and 1 assist in six games for the seventh-place squad.