The 2018 Thai League 2 is the 21st season of the Thai League 2, the second-tier professional league for Thailand's association football clubs, since its establishment in 1997, also known as M-150 Championship due to the sponsorship deal with M-150. A total of 15 teams will compete in the league. The season began on 9 February 2018 and is scheduled to conclude on 29 September 2018. Chainat Hornbill are the defending champions, while Samut Sakhon, Khonkaen and Udon Thani have entered as the promoted teams from the 2017 Thai League 3.