The National Championship was the next stage from the regional stage of 2022–23 Thai League 3.
The winners and runners-ups of each region[1] would qualify for this round to find 3 clubs promoting to 2023–24 Thai League 2.
Winners, runners-up, and third place of 2022–23 Thai League 3 would be promoted to the 2023–24 Thai League 2.
Dragon Pathumwan Kanchanaburi won 3–2 on aggregate.
MH Nakhon Si City won 2–1 on aggregate.