The 2021-22 season is Port's 5th consecutive seasons in top flight after promoted back from Thai League 2 in 2017.

Also, as Port finished 2nd in the first half of 2020-21 Thai League 1, they are qualified to the group stage of 2021 AFC Champions League.

The season was supposed to start on 31 July 2021 and concluded on 21 May 2022.

[1] Then, due to the situation of the COVID-19 pandemic is still severe, FA Thailand decided to postpone the season to start on 13 August 2021 instead.

Therefore, FA Thailand decided to postpone the opening day for the second time to start on 3 September 2021.