A native of Charlottetown, Prince Edward Island, Johnston played with three teams over four seasons in the Quebec Major Junior Hockey League and had 32 points (18 goals, 14 assists) in 44 games with Charlottetown in 2014-15. He signed with the Islanders as an undrafted free agent on March 31, 2015.

Johnston split the 2015-16 season between Bridgeport of the American Hockey League and Missouri of the ECHL but made his NHL debut against the Philadelphia Flyers on April 10, 2016.

Johnston split the 2017-18 season between Bridgeport and New York and got his first NHL point against the Chicago Blackhawks on Jan. 20, 2018, then scored his first goal on Jan. 25 against the Vegas Golden Knights. He finished with six points (three goals, three assists) in 24 NHL games and signed a four-year contract with the Islanders on July 9, 2018.

Johnston played the 2018-19 season with New York in a reserve role and scored four points (one goal, three assists) in 17 games. He had four points (three goals, one assist) in 32 games when the 2019-20 NHL season was paused March 12 due to concerns surrounding the coronavirus.

NOTES & TRANSACTIONS

• Signed as a free agent by NY Islanders, March 31, 2015.