Tamil Nadu State Transport Corporation Ltd. - (TNSTC) is a government owned public transport bus operator in Tamil Nadu, India. It operates Intercity bus services to cities within Tamil Nadu, and from Tamil Nadu to its neighbouring states. It also operates town busses from major cities and towns of Tamil Nadu to its neighbourhoods, with the exception of Chennai, where the public bus service is operated by MTC, a subsidiary of TNSTC. It is a bus operator with over 20258 buses and 17 million daily ridership.

Cd by the Government of Tamil Nadu. TNSTC has started online booking facilities to book bus tickets between major cities served by TNSTC. It caters to all the districts within Tamil Nadu and also operates services to neighbouring states of Andhra Pradesh, Karnataka, Kerala and union territory of Puducherry. Until 1997, the transport corporation was divided into 21 divisions which were later merged to form 8 divisions. TNSTC along with its subsidiaries, owns 321 depots and five workshops with a combined fleet strength of 21,678 buses. TNSTC also offers contract and tourist services. Every bus owned by the corporation displays a portrait of Tamil poet Thiruvalluvar along with a two-line verse from Thirukkural inside the bus.

The planning commission, in consultation with this ministry, has advised the state government to set up a road transport corporation under the Transport Corporations Act and the matter is under the consideration of the state government. Operation of nationalized transport services through a corporation is favoured so as to achieve railroad coordination, and to ensure operation on business lines. The general policy of the government is to establish corporations and the planning commission have advised that if the state governments want to nationalise the road services, they should form corporations and they should not be run as far as possible through government departments. It has also been suggested by the planning commission that the railways should participate or contribute to the state governments for running all the nationalised road services only when they decide to set up a corporation.

All the road transport corporations named after a popular or historical figure were changed to the current names after caste violence erupted between the caste groups of Devendrakula Velalars and Maravars in Virudhunagar district (then Kamarajar district), after the formation of Veeran Sundaralingam Transport Corporation (VSTC) by the bifurcation of Pandiyan Roadways Corporation (PRC). The Maravars opposed the naming of the new corporation on Veeran Sundaralingam, who is supposedly believed from the Devendrakula Velalar community.

In 1984, Tamil Nadu State Transport Corporation Limited established the Institute of Road and Transport Technology in Erode as the automobile research oriented institute with the vast area of 396 acres. It is a government institution listed as a category 1 college by the Directorate of Technical Education, Tamil Nadu.

In 1992, TNSTC established IRT Perundurai Medical College in Erode. It was established along the Perundurai Sanatorium which was running from 1930. The college has 600 beds and started functioning in 1992. In 2004, doctors' quarters were added. In 2008, a school of nursing has been started in the RTS Hospital premises. And in 2017, the strength of the Medical College was increased from 60 to 100 students intake.

In 1992-1993 TNSTC established IRT Polytechnic colleges (now undertaken by Government of Tamilnadu) in Thirunelveli and Bargur.

TNSTC also established In 2013, Tamil Nadu State Transport Corporation Limited established Amma Kudineer (Amma packaged drinking water) which is involved in the production and packaging of mineral water in one-litre plastic bottles, and selling them in long-distance running state-owned buses and in bus stations. The price has been fixed at ₹10 per bottle, and the production plant is set up in Gummidipoondi in Thiruvallur district. This venture is closed.