At the UK 2011 census, the ward of Oldbury had a population of 13,606, while the wider built-up area had a population of 23,964. However, Sandwell Metropolitan Borough Council give the population figure for Oldbury as 50,641.
Oldbury was part of the ancient parish of Halesowen, a detached part of Shropshire surrounded by Worcestershire and Staffordshire, until the Counties (Detached Parts) Act 1844, when it was incorporated back into Worcestershire after an absence of nine-hundred years. It became an Urban District in 1894, receiving Municipal Borough status in 1935.
In 1966, Oldbury was merged with the County Borough of Smethwick and the Municipal Borough of Rowley Regis to form the County Borough of Warley, which also included most of the Tividale area of Tipton and the eastern section of Oakham in Dudley. The geographical county boundaries were also changed to include the whole of Warley as part of Worcestershire; formerly both Rowley Regis and Smethwick had been in Staffordshire.
In 1974, Oldbury became part of the new Sandwell Metropolitan Borough, (a merger between the county boroughs of West Bromwich and Warley), and was transferred into the West Midlands Metropolitan County. Since 1986, after the abolition of the West Midlands County Council, Sandwell effectively became a unitary authority. Sandwell Council's headquarters are situated in Oldbury Town Centre.