Part of Southern Railway, Tamil Nadu has a well-developed and well-networked railway system. The headquarters of Southern Railway is in Tamil Nadu. Southern Railway covers the states of Tamil Nadu, Kerala, Puducherry, parts of Karnataka and Andhra Pradesh.

The state capital, Chennai, has direct express trains to metro towns in the country. Travellers can find numerous trains to Delhi, Mumbai, Bengaluru, Hyderabad and Kochi. Puratchi Thalaivar Dr M.G. Ramachandran Central Railway Station is the gateway to trains towards the north and Chennai Egmore is the hub of trains towards the south.

The major railway junctions in the state are Chennai, Coimbatore, Katpadi, Madurai, Salem, Erode, Dindigul, Karur, Nagercoil, Tiruchirapalli and Tirunelveli. The state has a total railway track length of 5,952 km (3,698 miles) and there are 532 railway stations in Tamil Nadu.

The Nilgiri Mountain Railway is a UNESCO World Heritage Site connecting Ooty on the hills and Mettupalayam in the foothills. The centenary-old Pamban Bridge over sea connecting Rameswaram in Pamban island to the mainland is an engineering marvel. It is one of the oldest cantilever bridges which are still in operation.

Chennai has a well-established suburban railway network and it is easy to commute between towns through the network.  Chennai Metro, that became operational in 2015, is the fourth longest metro system in India and serves the city of Chennai.