Jagiellonia II

Reserve sides in Poland exist to feed the first team, not to chase honours, and Jagiellonia's was set up in 1920, the same year as the parent club, itself formed by soldiers of the 42nd Infantry Regiment. Bartłomiej Drągowski moved through it on his way to the Polish national goal, and Jacek Bayer, who came through the same pipeline decades earlier, was the first Jagiellonia player capped by Poland at all.

Poland's rules keep reserve teams capped at the third tier regardless of form, so the side has never had a route to anything higher than the III Liga, currently Group I. That ceiling has not stopped it collecting regional silverware: promotion out of the IV Liga Podlasie came in 2019–20, and the club added the Podlaskie regional cup in 2022–23, on top of a run of district cup wins through the 1980s and early 1990s.

The team trains and plays at the Jagiellonia training centre on Elewatorska, holding around 1,000. Derby fixtures against Wigry Suwałki and Olimpia Zambrów carry the label "Derby Podlasia."

Tomasz Kulhawik currently runs the side, most recently trying that with the Greek forward Dimitrios Retsos, sent down for adaptation in August 2024. The group sits in the III Liga with promotion off the table by rule, its season judged instead by who graduates from it.