The Ayrshire Miners' Union was a coal mining trade union based in Scotland.
The first Ayrshire Miners' Union was founded in 1880, with Keir Hardie as its organiser. The union supported a strike for higher wages over the winter of 1881/82, but this was unsuccessful, and the union dissolved.
A new union was founded in 1886, with its Hardie elected as its first secretary. In 1893, it was reorganised on a federal basis and renamed the Ayrshire Miners' Federal Union. It was a founder of the Scottish Miners' Federation (SMF) in 1894, and by 1897 it claimed 3,000 members out of a total workforce of 10,000 in the county, making it the third largest component of the Federation.
In 1944, the SMF became the unitary National Union of Scottish Mineworkers, and the union became its Ayrshire District, with less autonomy than before.