The bank was opened to the public by T. V. Balagurusamy Nadar on 11 November 1921 in Ana Mavanna Building at South Raja Street, Thoothukudi.

On 6 September 2021, the Tamilnad Mercantile Bank filed a draft red herring prospectus with the Securities and Exchange Board of India to raise funds through an initial public offering.

[12][13] On 7 June 2022, the company received approval from the Securities and Exchange Board of India for its Initial public offering.

Today all 509 branches of the bank are networked using Infosys's "FINACLE" Software and have achieved 100% connectivity.

Tie-up arrangement made with Western Union Money Transfer, UAE Exchange & Financial Services...etc.

TMB entered the commodity futures market by becoming a clearing bank for NCDEX and MCX.

[6] The bank achieved a turnover of ₹15,726 crores in foreign exchange for the year ended March 2019.

[7] In terms of forex turnover, TMB ranks first among the Tamil Nadu-based private sector banks.