[3] The reserve team made their first appearance in Sikkim Gold Cup in 27 October 2018 and played their first ever match against fellow Kolkata side George Telegraph S.C.[4] The young side of ATK thrashed their comparatively experienced opponent by a margin of 5-1 goals to book their berth in the semi-final of the tournament.

On 13 July 2019, it was announced that reserves will play in the Calcutta Football League 2019 Division 1, a third tier competition in CFL pyramid.

[5] ATK Reserves started the season with a comfortable 0-2 victory against city rivals Mohammedan SC at Kalyani Stadium.

ATK colts lost the next match to TRAU at home before winning against Jamshedpur FC Reserves by a 2-0 margin.

The joint highest goalscorers for ATK Reserves were captain Yumnam Gopi Singh and Thomyo Simray, both finishing the season with 5 goals.

ATK U18 team played in the Hero Elite League and was placed in the Kolkata Zone along with East Bengal FC, Mohun Bagan, SAI Kolkata, United SC and Rainbow A.C.[8] They finished third in the 2018 Hero Elite League zonal phase behind Mohun Bagan and East Bengal.