The 1990–91 Yugoslav Second League season was the 45th season of the Second Federal League (Serbo-Croatian: Druga savezna liga), the second level association football competition of SFR Yugoslavia, since its establishment in 1946.
A total of 19 teams contested the league, including fourteen sides from the 1989–90 season, one club relegated from the 1989–90 Yugoslav First League and four sides promoted from the Inter-Republic Leagues played in the 1989–90 season.
Two points were awarded for a win, while in case of a draw - penalty kicks were taken and the winner of the shootout was awarded one point while the loser got nothing.
The four clubs promoted to the second level were Bor, Mogren, Radnički Belgrade and NK Zagreb.
After the secession of Croatia, four clubs were selected by the Federation between different Republics.