UBI was the result of the merger in 1950 of four Bengali banks: Comilla Banking Corporation (founded by Narendra Chandra Dutta in 1914 in what is now Bangladesh), Bengal Central Bank (founded by Sri J.C. Das in 1918), Comilla Union Bank (founded by Sri L.B. Dutta in 1922) and Hooghly Bank (founded by Sri D.N. Mukherjee 1932). All four had suffered runs in December 1950 after the failure of the Nath Bank. The Reserve Bank of India assisted the banks in amalgamating to form United Bank of India. In 1961, UBI merged with Cuttack Bank (est. 6 June 1913) and Tezpur Industrial Bank (est. 6 June 1918, as the first commercial bank in Assam province). Four years later, in 1965, the Government of Pakistan took over the bank's branches in Pakistan. On 19 July 1969, the Government of India nationalised UBI, along with 13 other major Indian commercial banks. At the time of nationalization UBI had only 174 branches. In 1973, UBI acquired Hindustan Mercantile Bank (est. 1944). In 1976, UBI acquired Narang Bank of India, which had been established in 1943 in Narang, Gujarat.
Today, United Bank of India (UBI) is an Indian government-owned financial services company headquartered in Kolkata, India. Presently the bank has a three-tier organisational setup consisting of its head office in Kolkata, 35 regional offices and 2005 branches spread all over India. However, its major presence is in Northern India. The bank has three full-fledged overseas branches, one each at Kolkata, New Delhi and Mumbai. United Bank of India now aims to expand its international activities. On 30 March 2009, the Indian government approved the restructuring of United Bank of India. The government proposed to invest 2.5 billion rupees in shares by 31 March and another 5.50 billion in the next fiscal year in Tier-I capital instruments. The move is part of the Indian government's program to improve the capital base of the state-owned banks.