The 2020–21 Croatian Second Football League (also known as Druga HNL and 2. HNL) was the 30th season of the Croatian Second Football League, the second-level football competition for men's association football teams in Croatia, since its establishment in 1992. The season started on 13 August 2020 and ended on 29 May 2021. The league was contested by 18 teams, two more than the previous season, and played in a double round robin format, with each team playing every other team twice over 34 rounds.