The 2020–21 III liga season was the 13th edition of the fourth tier domestic division in the Polish football league system since its establishment in 2008 under its current title (III liga) and the 5th season under its current league division format.

The competition was contested by 84 clubs split geographically across 4 groups, with the winners of each group gaining promotion to the II liga.

From October 17, 2020, due to the COVID-19 pandemic restrictions, all III liga football matches take place behind closed doors without any spectators.

[2] 84 teams are divided into four groups according to geographical criteria:

Each group of III liga is managed by a different voivodship football association.