Elected county councils were created in 1889 under the Local Government Act 1888, taking over many administrative functions that had previously been performed by unelected magistrates at the quarter sessions.

The borough of Poole had been a county corporate since 1568, independent from the Sheriff of Dorset,[1] but it was not considered large enough to take on county-level functions under the 1888 Act.

The county council formally came into being on 1 April 1889, on which day it held its first official meeting at the Municipal Buildings in Dorchester.

In terms of territory, Dorset gained Bournemouth (which had been a county borough since 1900), Christchurch, and part of the Ringwood and Fordingbridge Rural District from Hampshire.

[11] That was followed by a series of public consultations and, ultimately, by statutory instruments for the reform of local government across Dorset, drawn up in May 2018.

Under these proposals, dubbed "Future Dorset", all existing councils within the county would be abolished and replaced by two new unitary authorities.

[12] Dorset County Council's responsibilities included schools, social care for the elderly and vulnerable, road maintenance, libraries and trading standards.

[19][20] From 1889 until 1955 the council met at Shire Hall on High West Street in Dorchester (which also retained its primary function as a courthouse during that time).