The 2018 Thai League 1 is the 22nd season of the Thai League 1, the top Thai professional league for association football clubs, since its establishment in 1996, also known as Toyota Thai League due to the sponsorship deal with Toyota Motor Thailand. A total of 18 teams will compete in the league. The season began on 9 February 2018 and is scheduled to conclude on 7 October 2018.
Buriram United are the defending champions, while Chainat Hornbill, Air Force Central and Prachuap have entered as the promoted teams from the 2017 Thai League 2.
The 1st transfer window is from 14 November 2017 to 5 February 2018 while the 2nd transfer window is from 1 June 2018 to 29 June 2018.
Promoted from the 2017 Thai League 2
Relegated from the 2017 Thai League
Note: Flags indicate national team as has been defined under FIFA eligibility rules. Players may hold more than one non-FIFA nationality.
A T1 team could registered five foreign players by at least one player from AFC member countries and at least one player from ASEAN member countries. A team can use four foreign players on the field in each game, including at least one player from the AFC member countries or ASEAN member countries (3+1).
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Source: Thai League