In the 2020–21 season, Stal Mielec competed in the Ekstraklasa.

[3] Moreover, they participated in the season's Polish Cup edition, since they were eliminated by Piast Gliwice, following a 1–1 draw (3–4 on penalties) in the round of 32.

[4] Note: Flags indicate national team as defined under FIFA eligibility rules; some limited exceptions apply.

Players may hold more than one non-FIFA nationality.

° symbol applies for players who joined the club in the pre-season term.