- On 22 May 2019 Kaliakra 1923-Levski 2012 (Kavarna) is renamed to Kaliakra 1923. The name change comes into force with the start of this season.
- On 7 August 2019 Lokomotiv (Ruse) withdraws due to organizational and financial reasons. ZS Varna is to confirm their withdrawal from the group.
- On 8 July 2019 Yantra Gabrovo (Gabrovo), 2nd last season; Yantra 1919 (Gabrovo), 1st in OG Gabrovo last season; and Chardafon 1919 (Gabrovo), 5th in OG Gabrovo last season; merge into Yantra 2019 (Gabrovo).
- On 17 July 2019 newly promoted Chiko Bunara (Byaga) declines participation in Treta liga due to financial constraints. ZS na BFS - Sofia decides that the group remains with 17 teams for this season.
- Kyustendil (Kyustendil) plays its home games at the "Osogovo" st. in Kyustendil.
- On 14 June 2019 STK removes Vereya (Stara Zagora) from the group, due to a decision by the Licensing commission from 4 June 2019 g., which entered into force on 13 June 2019. Vereya can enter in Yugoiztochna Treta liga, but doesn't register for participation by the deadline - 13 July 2019.
- Dimitrovgrad 1947 (Dimitrovgrad) plays its home games at the "Minyor" st. in Dimitrovgrad.
- Maritsa 1921 (Plovdiv plays its home games at the "Maritsa" st. in Plovdiv.
- Rozova dolina (Kazanlak) plays its home games at the "Sevtopolis" st. in Kazanlak.
- Haskovo 1957 (Haskovo) plays its home games at the "Haskovo" st. in Haskovo.
- Chernomorets 1919 (Burgas) plays its home games at the "Chernomorets" st. in Burgas.