An election to Belfast Corporation took place in January 1920 as part of that year's Irish local elections. The Local Government (Ireland) Act 1919 had seen elections for local government in Ireland change to a more proportional system. As a result, Unionist dominance of the Belfast council was somewhat undermined, and the party lost 15 seats. In contrast Labour, Sinn Féin, and Nationalist representation grew, resulting in a more politically and socially representative council. After the election Sir William Coates, 1st Baronet was elected by the new council as Lord Mayor of Belfast.