2018–19 Slovenian Third League

The 2018–19 Slovenian Third League was the 27th edition of the Slovenian Third League. The season began on 17 August 2018 and ended on 2 June 2019.

Competition format and rules
In the 2018–19 season, the Slovenian Third League (3. SNL) was divided into four regional groups with a total of 38 participating clubs. The three groups (North, Centre, East) were composed of ten clubs, while the West group consisted of eight clubs. The group winners played a two-legged play-off for promotion to the Slovenian Second League.

3. SNL Centre
Zarica Kranj withdrew and were replaced by Žiri one week before the start of the season.

Clubs
A total of ten teams competed in the league, including nine sides from the 2017–18 season and one team relegated from the 2017–18 Slovenian Second League (Veržej).

Play-offs
A two-legged play-offs between the group winners for promotion to the Slovenian Second League.