An Order in Council changed The Shire of Barkly Tableland to The Shire of Mount Isa on 15 December 1962, effective from 1 July 1963. The change was made under The Local Government Act 1936 – 1961. The new Shire also included part of The Shire of Cloncurry.
Under the Local Authorities Act 1902, the primary function of Shire Councils was to provide such public services and amenities as parks and reserves, cemeteries, libraries and recreational facilities, water and sanitation services, roads, bridges, wharves, street lighting, public health services (such as immunisations), licences and registrations for businesses, markets and animals, town planning, and the control of noxious weeds and other pests.
The Council was also responsible for administering the Local Fund, and for valuing properties within the Shire for the purposes of determining and collecting rates. The Council could pass by-laws regarding all matters within its jurisdiction. All such by-laws required the assent of the Governor-in-Council.
The Shire Council included a chairman and up to eleven, but no less than five members. From time to time, the Council could appoint committees for special or general purposes. Council also appointed its own officers including a Shire Clerk who were paid from the Local Fund. Each year the Minister appointed an independent auditor to review the financial statements of the Council.
Mount Isa was declared a city due to its growing population. The Mount Isa Shire was abolished on 30 May 1968 and its functions transferred to the newly formed Mount Isa City Council.