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 M-150. A total of 18 teams will compete in the league. The season is scheduled to begin on 14 August 2021 and is scheduled to conclude on 22 May 2022.

For this season two teams in the final table (champion and runner up) directly promoted to Thai League 1 next season while teams ranked 3rd - 6th qualified in play off for last spot in top tier next season.

The 1st transfer window is from 4 May 2021 to 27 July 2021 while the 2nd transfer window is from 8 December 2021 to 4 January 2022.

Team changes
The following teams have changed division since the 2020–21 season.

To Thai League 2

 * Promoted from Thai League 3


 * Lamphun Warriors
 * Muangkan United
 * Rajpracha
 * Relegated from Thai League 1


 * Sukhothai
 * Trat
 * Rayong

From Thai League 2

 * Promoted to Thai League 1


 * Nongbua Pitchaya
 * Chiangmai United
 * Khonkaen United


 * Relegated to Thai League 3


 * Samut Sakhon
 * Sisaket
 * Uthai Thani

Renamed Clubs

 * MOF Customs United renamed to Customs Ladkrabang United

Personnel
Note: Flags indicate national team as has been defined under FIFA eligibility rules. Players may hold more than one non-FIFA nationality; Club dissolved during season would shown by grey background.

Foreign Players
Players name in bold indicates the player was registered during the mid-season transfer window.

Semi-finals
Lampang won 4–1 on aggregate.

Trat won 2–1 on aggregate.

Finals
''5–5 on aggregate. Lampang won on away goals.''

Top scorers

 * As of 30 April 2022.

Clean sheets

 * As of 30 April 2022.