The Slovenian Third Football League (Slovene: Tretja slovenska nogometna liga or commonly 3.

In the 1998–99 season, the league was expanded to four regional groups (Centre, East, North, West).

Due to the expansion of the Slovenian Second League, the top two teams in each of the four groups were promoted in the 2016–17 season.

In the 2018–19 season, the North, Centre and East groups were reduced to ten teams.

After the season, the old system with two groups (East and West) with both winners promoting to the Second League was reintroduced.