2019 Thai League 1
Buriram United are the defending champions , while PTT Rayong , Trat and Chiangmai have entered as the promoted teams from the 2018 Thai League 2 . 
<triplet> 2018 Thai League 2 <subj> PTT Rayong <obj> promoted <subj> Trat <obj> promoted <subj> Chiangmai <obj> promoted