[2] However, on March 4, the decision changed to postpone all of matches prior to 18 April due to the COVID-19 pandemic in Thailand.
Chainat Hornbill and Chiangmai were relegated at the end of the 2019 season after finishing in the bottom two places of the table.
The FIFA Transfer Window Period for Thailand was 19 November 2019 to 10 February 2020, and 15 June to 12 July 2020.
[5] The Round 15 match between Chiangrai United and Port, originally scheduled to be played on 5 January 2021, was postponed along with all matches in January 2021 due to the COVID-19 pandemic in Thailand, and could not be played before the 2021 AFC Champions League group stage draw on 27 January 2021, and thus this match would not be taken into account when ranking the third-placed and fourth-placed teams between Chiangrai United and Ratchaburi Mitr Phol.
The top four teams after the first half of the season (Round 15) qualified for the 2021 AFC Champions League.