The National Championship was the next stage from the regional stage of
2020–21 Thai League 3. The winners and runners-ups of each region would qualified to this round to finding three clubs promoting to the
2021–22 Thai League 2
The 2021–22 Thai League 2 is the 24th season of the Thai League 2, the second-tier professional league for Thailand's association football clubs, since its establishment in 1997, also known as M-150 Championship due to the sponsorship deal with ...
.
Teams
Note:
Qualifying play-offs
Play-off round
, -
!colspan=3, Northern region
, -
!colspan=3, Bangkok metropolitan region
:Northern region
:Bangkok metropolitan region
Group stage
Upper region
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Lower region
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Knockout stage
Winners, runners-up, and third place of
2020–21 Thai League 3 would be promoted to the
2021–22 Thai League 2
The 2021–22 Thai League 2 is the 24th season of the Thai League 2, the second-tier professional league for Thailand's association football clubs, since its establishment in 1997, also known as M-150 Championship due to the sponsorship deal with ...
.
Third place play-off
Summary
Matches
''Rajpracha won 2–1 on aggregate.''
Final
Summary
Matches
=1st leg
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=2nd leg
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''Lamphun Warriors won 3–2 on aggregate.''
Statistics
Goalscorers
Teams promoted to 2021–22 Thai League 2
:* Lamphun Warriors (champions)
:* Muangkan United (runners-up)
:* Rajpracha (third-placed)
References
{{DEFAULTSORT:2020-21 Thai League 3 National Championship
Thai League 3
3