The 1984–85 Yugoslav Second League season was the 39th 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 eighteen teams contested the league, including twelve sides from the 1983–84 season, two clubs relegated from the 1983–84 Yugoslav First League and four sides promoted from the Inter-Republic Leagues played in the 1983–84 season.
The four clubs promoted to the second level were Crvenka, Maribor, Rudar Ljubija and RNK Split.
A total of eighteen teams contested the league, including fourteen sides from the 1983–84 season and four sides promoted from the Inter-Republic Leagues played in the 1983–84 season.
There were no teams relegated from the 1983–84 Yugoslav First League and four clubs promoted to the second level were Bregalnica Štip, Liria, Novi Pazar and OFK Titograd.