The county councils created under British rule in 1899 continue to exist in Ireland, although they are now governed under legislation passed by Oireachtas Éireann, principally the Local Government Act 2001.
The Local Government (Ireland) Act 1898 introduced county councils to Ireland. The administrative and financial business carried by county grand juries and county at large presentment sessions were transferred to the new councils. Principal among these duties were the maintenance of highways and bridges, the upkeep and inspection of lunatic asylums and the appointment of coroners. The new bodies also took over some duties from poor law boards of guardians in relation to diseases of cattle and from the justices of the peace to regulate explosives.
The Irish county councils differed in constitution from those in Great Britain. Most of the council was directly elected: each county was divided by the Local Government Board for Ireland into electoral divisions, each returning a single councillor for a three-year term. In addition urban districts were to form electoral divisions: depending on population they could return multiple county councillors. The county councils were also to consist of "additional members":
- The chairman of each rural district council in the county was to be an ex officio member. Where the chairman had already been elected to the council or was disqualified, the RDC was to appoint another member of their council to be an additional member.
- The council could also co-opt one or two additional members for a three-year term.
The first county council elections were held on 6 April 1899, and the first business of their inaugural meetings being the appointment of additional members. The triennial elections were postponed in 1914 on the outbreak of World War I.
The Local Government (Ireland) Act, 1919 introduced proportional representation to county councils: all councillors were to be elected by single transferable vote from multi-member electoral areas. There was only one election under the new system, held in January 1920 (in urban areas) and on 2 June 1920 (in rural areas), during the Irish War of Independence.
1922 to present
The Irish Free State inherited the local authorities created by the United Kingdom legislation of 1898 and 1919, and elections were held on 23 June 1925. The first native legislation was the Local Government Act 1925. The act abolished rural district councils (except in County Dublin) and passed their powers to the county councils. At the following election all county councils were to be increased: the number of extra councillors was to be twice the number of abolished rural districts. The act set out the powers and duties of county councils and also gave the Minister for Local Government the power to dissolve councils if he was satisfied that "the duties of a local council are not being duly and effectually discharged". He could order new elections to be held, or transfer the power and properties of the council "to any body or persons or person he shall think fit". The power was widely used by ministers of all parties. For example, Kerry County Council was dissolved from 1930 to 1932, and from 1945 to 1948, with commissioners appointed to perform the council's function.
The number of county councils was increased from twenty-seven to twenty-nine in 1994 when the Local Government (Dublin) Act 1993 split County Dublin into three counties: Dún Laoghaire–Rathdown, Fingal and South Dublin.