Muangthong United are the defending champions, having won their Thai Premier League title the previous season.

TTM Chiangmai, BBCU and Singhtarua were relegated to the 2013 Thai Division 1 League after finishing the 2012 season in the bottom three places.

They were replaced by the best three teams from the 2012 Thai Division 1 League champions Ratchaburi, runners-up Suphanburi and third place Bangkok United.

Esan United were originally replaced by Sisaket, but it was discovered the move from Sisaket to Uban Ratchathani (and as a consequence thereof naming the club Esan United) was facilitated with forged documents, fraud and other criminal activity.

[2][3] Note: Flags indicate national team as has been defined under FIFA eligibility rules.