Colchester and Ipswich to play Gills in Papa John's group stages.
Gillingham have discovered two of their three Papa John's group stage opponents ahead of the 2021/22 competition.
Ipswich Town and Colchester United have been drawn in group A of the southern section, along with the Gills, with an additional U21 invited club yet to be selected.
Last season the Gills played Crawley, Ipswich and Arsenal U21 in the tournament, getting through the group stages before falling 2-0 to Cambridge in round two.
The first round of games are set to take place the week commencing August 30, however this is subject to Carabao Cup progression.
Other fixtures dates, and invited U21 sides, can be viewed here.