South Indian Bank was registered in 1929 under the Companies Act.[7] It commenced business on 29 January 1929 at Round South, Thrissur.

It was included in the second schedule of the Reserve Bank of India and became a scheduled Bank on 7 August 1946. SIB was the first scheduled Bank in the private sector in Kerala to get the license under Section 22 of the Banking Regulation Act, 1949 from the RBI on 17 June 1957.