The 2020–21 ABA League Second Division was the 4th season of the ABA Second Division with 14 teams from Bosnia and Herzegovina, Croatia, Montenegro, North Macedonia, Serbia, and Slovenia participating in it. The season has started on 9 November 2020. The season was the first to be played after the previous season was abandoned due to the COVID-19 pandemic. In accordance with the COVID-19 situation, it has been determined that the season will be played in new competition format and new calendar.