The champions league round was the next stage from the regional stage of 2018 Thai League 4. The winners of each regions, the runners-up of some regions, and the winners of qualifying play-off would qualified to this round to finding 3 clubs promoting to 2019 Thai League 3.
| Team | Qualifying method | ||
|---|---|---|---|
| Group stage direct entrants | |||
| Uttaradit | Northern region champions | ||
| Muang Loei United | Northeastern region champions | ||
| Khon Kaen United | Northeastern region runners-up | ||
| Bankhai United | Eastern region champions | ||
| Chanthaburi | Eastern region runners-up | ||
| Nakhon Pathom United | Western region champions | ||
| IPE Samut Sakhon United | Western region runners-up | ||
| Satun United | Southern region champions | ||
| North Bangkok University | Bangkok Metropolitan region champions | ||
| Qualifying play-off participants | |||
| Entering in play-off round | |||
| Nan | Northern region runners-up | ||
| Huahin City | Western region runners-up | ||
| Pattani | Southern region runners-up | ||
| Grakcu Saimai United | Bangkok Metropolitan region third place | ||
| Entering in preliminary round | |||
| Yasothon | Northeastern region third place | ||
| Pluakdaeng Rayong United | Eastern region third place | ||
| Hatyai | Southern region third place | ||
| BGC | Bangkok Metropolitan region fourth place | ||
Upper region
Lower region
|-!colspan=3|Upper region|-!colspan=3|Lower region|}
Upper region
Lower region
|-!colspan=3|Upper region|-!colspan=3|Lower region|}
Upper region
Lower region
Winners, runners-up, and third place of 2018 Thai League 4 would promoted to 2019 Thai League 3.
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North Bangkok University won 2–1 on aggregate.
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Nakhon Pathom United won 5–4 on aggregate.
Maranhão (North Bangkok University) Jardel Capistrano (Khon Kaen United) Olveira Silva Diego (Nakhon Pathom United)
Chamsuddeen Shoteng (Satun United) João Francisco (North Bangkok University) Poomipat Kantanet (North Bangkok University) Martins Caio Henrique (Satun United) Natthawut Munsuwan (Satun United) Chainarong Samuttha (Chanthaburi) Charin Buthad (Khon Kaen United) Chanukun Karin (North Bangkok University)
Diop Badara Aly (Yasothon) Kaikitti Inuthen (Bankhai United) Piya Kruawan (Bankhai United) Krittanon Thanachotjareanphon (Grakcu Saimai United) Chatchai Phithanmet (Huahin City) Tebnimit Buransri (Khon Kaen United) Nakun Phintong (Nakhon Pathom United) Pongsathon Tongchaum (Nakhon Pathom United) Pattanapong Chumchan (Yasothon) Vichit Singloilom (Yasothon)
Camara Souleymane (Bankhai United) Chokchai Sukthed (Bankhai United)
Elvis Job (Bankhai United) Pongrawit Jantawong (BGC) Thammayut Rakbun (BGC)
Ozor Enoch (Chanthaburi) Tripop Jaroensheep (Chanthaburi) Rattikun Plonghirun (Grakcu Saimai United) Samart Phetnoo (Grakcu Saimai United) Amorn Mudlied (Hatyai) Anon Kaimook (Huahin City) Panudach Subpeng (Huahin City) Songkran Puangnoy (Huahin City) Kissi Koffi Ludovic Loic (IPE Samut Sakhon United) Pantakan Kasemkulwirai (IPE Samut Sakhon United) Phethai Sa-ngiamsak (IPE Samut Sakhon United)
Abass Ouro-Nimini (Muang Loei United) André Houma Ekue (Muang Loei United) Chawin Thirawatsri (Muang Loei United) Krit Phavaputanon (Muang Loei United) Chokchai Chuchai (Nakhon Pathom United) Lesley Ablorh (Nakhon Pathom United) Nattaphon Worasut (Nakhon Pathom United)
Saeid Chahjouei (Nakhon Pathom United) Wisarut Pannasi (Nakhon Pathom United) Jettarin Phetborisut (Pluakdaeng Rayong United) Fabricio Marabá (Satun United) Manso Ausman (Satun United) Thanakorn Sathanpong (Satun United) Thirawat Lertpitchapatch (Satun United) Diarra Aboubacar Sidick (Uttaradit) Kritnapop Mekputcharakul (Uttaradit) Patipat Kamsat (Uttaradit) Otis Sarfo Adjei (Yasothon) Tanakit Wonglikit (Bankhai United against Chanthaburi) Panadon Lexsuwan (Chanthaburi against Muang Loei United) Yongyut Jareonpoom (Chanthaburi against Muang Loei United) Chatchai Maneewan (Grakcu Saimai United against Pattani)