Elected county councils were created under the Local Government Act 1888, taking over many administrative functions that had previously been performed by magistrates at the Quarter Sessions.

The first chairman of the council was Andrew Johnston of Woodford, a Liberal, who held the post for 27 years until he stood down in 1916.

The county was divided into 14 non-metropolitan districts at the same time, forming a lower tier of local government.

At the 2011 census Essex County Council served a population of 1,393,600, making it one of the largest local authorities in England.

County council functions include social care, transport, education and many others.

Political control of the county council since the reforms of the Local Government Act 1972 took effect on 1 April 1974 has been as follows:[12] The leaders of the council since 1996 have been:[13] Following the 2021 election and subsequent by-elections up to July 2024, the composition of the council was as follows:[14] The Canvey Island Independents, Green, Loughton Residents, Residents for Uttlesford, Rochford Residents and the three independent councillors all sit together as the "Non-aligned Group".

[21][22] The council's London premises at Finsbury Square were destroyed in the Blitz during the Second World War.