The National Championship was the next stage from the regional stage of 2021–22 Thai League 3. The winners and runners-ups of each region would qualify for this round to find 3 clubs promoting to 2022–23 Thai League 2.
The National Championship was the next stage from the regional stage of 2021–22 Thai League 3. The winners and runners-ups of each region would qualify for this round to find 3 clubs promoting to 2022–23 Thai League 2. (en)