Indian Overseas Bank (IOB) is a public sector bank headquartered in Chennai, India. Thiru. M. Ct. M. Chidambaram Chettyar founded it in 1937 to promote foreign trade and overseas banking.

IOB offers a range of banking and financial products and services to individuals, small and medium-sized enterprises, and large corporations. These include savings accounts, current accounts, retail products, Indian Overseas Bank cards, term deposits, and third-party insurance. The bank also provides corporate and rural banking services, such as micro, small, and medium enterprise schemes and merchant banking.

IOB has a strong presence in India, with a network of branches across the country, and also operates in other countries, including Singapore, Hong Kong, Sri Lanka, and Thailand. As of March 2022, IOB has 3,269 domestic branches, Digital Banking Units, and foreign branches and representative offices. IOB was one of the 14 major banks nationalized by the Indian government. In February 2024, Indian Overseas Bank reached ₹1 lakh crore in market capitalization, becoming the fifth public sector lender to reach this milestone