The 2020–21 Denmark Series was the 56th season of the Denmark Series, the fourth-tier of the Danish football league structure organised by the Danish FA (DBU).
The season marked a transitional phase in the structure of the Danish leagues.
This season, the league was divided in four groups of eleven teams each.
After the regular season, the top four teams in Groups 1 and 2 faced off in play-offs for a spot in the 2020–21 Danish 2nd Divisions, and the same was the case for Groups 3 and 4, which meant that two teams promoted.
The teams took all earned points and goals scored with them to the playoffs.