Established in 1992 as the Metropolitan Rapid Transit Authority and reorganized under the Mass Rapid Transit Authority of Thailand Act B.E. 2543 (2000), MRTA is a state enterprise operating under the Ministry of Transport. MRTA serves as the master planning body, infrastructure owner, procurement authority, and supervisor of mass rapid transit railway projects throughout the Bangkok Metropolitan Region and designated provincial urban centers including Chiang Mai, Phuket, Phitsanulok, and Nakhon Ratchasima.

MRTA oversees a diverse multi-modal urban rail ecosystem delivered primarily through Public-Private Partnership (PPP) concessions (such as Net Cost and Gross Cost concessions with Bangkok Expressway and Metro / BEM and Eastern Bangkok Monorail / Northern Bangkok Monorail consortia). Its operational and ongoing rail portfolio comprises heavy metro corridors like the underground and elevated MRT Blue Line (Chaloem Ratchamongkhon) and the elevated MRT Purple Line (Chalong Ratchatham), alongside the southern extension to Kru Nai. MRTA also commissioned Thailand’s first mass transit straddle monorail systems: the 30.4 km MRT Yellow Line (Lat Phrao–Samrong) and the 34.5 km MRT Pink Line (Khaerai–Min Buri).

Under the Mass Rapid Transit Master Plan in Bangkok Metropolitan Region (M-MAP), MRTA is managing the delivery of the MRT Orange Line megaproject—a strategic 35.9 km east-west transit backbone linking Bang Khun Non to Min Buri via deep mined/bored tunnels and elevated guideways—alongside common ticketing initiatives (Mangmoom / EMV contactless payment integration) and provincial light rail transit feasibility studies.