The 2015–16 Treća HNL season is the 25th since its establishment. The first matches of the season will be played on 22 August 2015, and the season will end on 4 June 2016.
50 teams will join the league, including one relegated from the 2014–15 Druga HNL and six promoted from the lower leagues.
| Competition: | Treća HNL East |
| Season: | 2015–16 |
| Winners: | Međimurje |
| League Topscorer: | 21 goals Nikola Valjak(Podravina) |
| Biggest Home Win: | Bjelovar 6−0 Slavonija Bjelovar 6−0 Mladost Antin Belišće 7−1 Podravina |
| Biggest Away Win: | Mladost Antin 1−10 Slavonija |
| Highest Scoring: | Belišće 9−4 Mladost Antin |
| Matches: | 240 |
| Total Goals: | 729 |
| Updated: | 4 June 2016 |
| Team | Home city | Stadium | Capacity | |
|---|---|---|---|---|
| Belišće | Belišće | Gradski stadion | 5,000 | |
| Bjelovar | Gradski stadion | 4,000 | ||
| BSK | Bijelo Brdo | Igralište BSK-a | 1,000 | |
| Đakovo | Stadion na Pazarištu | 3,000 | ||
| Koprivnica | Gradski stadion | 3,500 | ||
| Marsonia | Slavonski Brod | Stadion uz Savu | 8,000 | |
| Međimurje | Čakovec | SRC Mladost | 6,000 | |
| Mladost Antin | Antin | Paža | 500 | |
| Mladost Ždralovi | Ždralovi | Igralište NK Mladosti | 1,000 | |
| Oriovac | Igralište NK Oriolika | 1,500 | ||
| Podravina | Ludbreg | Igralište NK Podravine | 5,000 | |
| Pleternica | Stadion Stjepan Zdenko Šivo | 700 | ||
| Slavonija | Požega | Stadion kraj Orljave | 4,000 | |
| Varaždin | Varaždin | Stadion Anđelko Herjavec | 9,099 | |
| Višnjevac | Višnjevac | Stadion NK Višnjevca | 1,500 | |
| Vukovar '91 | Vukovar | Gradski stadion | 6,000 |
| Competition: | Treća HNL South |
| Season: | 2015–16 |
| Winners: | Solin |
| Promoted: | Solin |
| League Topscorer: | 22 goals Šime-Josip Pedišić (Val) |
| Biggest Home Win: | Hajduk II 5−0 Mosor Hrvace 5−0 Jadran LP Omiš 6−1 Croatia Zmijavci |
| Biggest Away Win: | Kamen Ivanbegovina 0−4 Hajduk II OŠK Otok 0−4 Junak Mosor 0−4 Val |
| Highest Scoring: | Kamen Ivanbegovina 5−3 Val |
| Matches: | 306 |
| Total Goals: | 819 |
| Updated: | 4 June 2016 |
| Team | Home city | Stadium | Capacity | |
|---|---|---|---|---|
| BŠK Zmaj | Blato | Zlinje | 3,000 | |
| Zmijavci | ŠRC Marijan Šuto Mrma | 1,000 | ||
| Hajduk II | Split | Poljud | 34,448 | |
| Hrvace | Hrvace | Gradski stadion | 3,075 | |
| Jadran LP | Ploče | Igralište NK Jadrana | 2,000 | |
| Junak | Sinj | Gradski stadion | 3,096 | |
| Kamen Ivanbegovina | Ivanbegovina | Igralište NK Kamena | 1,000 | |
| Mosor | Split | Stadion u Pricviću | 3,000 | |
| Neretva | Metković | Igralište iza Vage | 2,000 | |
| Opuzen | Podvornica | 2,500 | ||
| Omiš | Omiš | Stadion Anđelko Marušić-Ferata | 5,000 | |
| OŠK Otok | Otok | Igralište NK Otok | 450 | |
| Primorac B/M | Biograd na Moru | Gradski stadion Kazimir i Silvio | 1,500 | |
| Primorac 1929 | Stobreč | Igralište u Blatu | 3,600 | |
| Solin | Solin | Stadion pokraj Jadra | 5,000 | |
| Val | Kaštel Stari | Vukovar | 2,000 | |
| Zagora | Unešić | Borovište | 3,000 | |
| Zmaj Makarska | Makarska | Gradski sportski centar | 5,000 |
| Competition: | Treća HNL West |
| Season: | 2015–16 |
| Winners: | Novigrad |
| Promoted: | Novigrad |
| League Topscorer: | 19 goals Marko Bjelanović(Novigrad) |
| Biggest Home Win: | Zagorec 6−0 HAŠK |
| Biggest Away Win: | Stupnik 0−6 Vinogradar Stupnik 0−6 Novigrad |
| Highest Scoring: | Rijeka II 5−3 Dubrava Dugo Selo 3−5 Samobor |
| Matches: | 240 |
| Total Goals: | 625 |
| Updated: | 28 May 2016 |
| Team | Home city | Stadium | Capacity | |
|---|---|---|---|---|
| Dubrava | Zagreb | ŠRC Grana-Klaka | 2,000 | |
| Dugo Selo | Gradski stadion | 2,000 | ||
| HAŠK | Zagreb | ŠRC Pešćenica | 3,000 | |
| Krk | Krk | SRC Josip Uravić Pepi | 500 | |
| Maksimir | Zagreb | Oboj | 247 | |
| Novigrad | Novigrad | Lako | 2,300 | |
| Opatija | Opatija | Stadion NK Opatije | 2,000 | |
| Rijeka II | Rijeka | 5,786 | ||
| Samobor | Samobor | SC NK Samobor | 5,000 | |
| Gornji Stupnik | SRC Stupnik | 1,000 | ||
| Špansko | Zagreb | Stadion NK Špansko | 1,000 | |
| Trnje | Zagreb | Stadion Trnja | 1,000 | |
| Vinogradar | Jastrebarsko | Mladina | 2,000 | |
| Vrapče | Zagreb | Igralište Vrapča | 1,000 | |
| Vrbovec | Vrbovec | Gradski stadion kraj Sajmišta | 4,000 | |
| Zagorec | Krapina | ŠRC Podgora | 2,000 |