Tamilnad Mercantile Bank Limited was incorporated in the name of Nadar Bank Limited' on May 11, 1921 at Thoothukudi, Tamil Nadu as a limited company under Indian Companies Act, 1913 pursuant to a certificate of incorporation issued by the erstwhile Assistant Registrar of Joint Stock, Palamcottah.. Subsequently, name of the Bank was changed to Tamilnad Mercantile Bank Limited', with effect from November 27, 1962, pursuant to a letter of approval from the Government of India dated November 14, 1962 and a fresh certificate of incorporation dated July 17, 1968 was issued by the Assistant Registrar of Companies, Madras.
On November 11, 1921, the Bank commenced business at Thoothukudi, in Tamil Nadu. In 1933, it acquired its first property at Beach Road, Thoothukudi, in Tamil Nadu. On May 11, 1935, it was included in the second schedule to the Reserve Bank of India Act, 1934. It was granted the licence to carry on banking business in India by RBI on November 20, 1962. It opened a a rural branch at Vilathikulam, Tamil Nadu in 1968. In 1993, it was registered as Category-1 Merchant Bankers with SEBI and opened first currency chest at Madurai Branch.
The Bank was granted licence to deal in foreign exchange in 1999. It launched first ATM, christened as TMB Surabhi, in Chennai in 2004. In 2005, it launched first insurance linked deposit scheme, christened as Siranjeevee Recurring Deposit. It launched SMS banking services and internet banking facilities, christened as TMB E-Connect in 2008. It launched mobile banking facilities in 2012. It signed an agreement for the issuance of PAN cards in 2014.
The Bank was recognized as the 'Best Performing Bank' by Pension Fund Regulatory and Development Authority of India for outstanding performance under the 'Atal Pension Yojana' for the period 2020-2021. As of June 30, 2021, the Bank had 509 branches, of which 106 branches were in rural, 247 in semi-urban, 80 in urban and 76 in metropolitan centres. It built a strong presence in the state of Tamil Nadu, with 369 branches and 941 automated teller machines (ATMs) and 238 cash recycler machines (CRMs). The Bank offer a wide range of banking and financial services primarily to micro, small and medium enterprises (MSME), agricultural and retail customers, operating in manufacturing, trading and services sector.