Bute and Northern Ayrshire was a county constituency of the House of Commons of the Parliament of the United Kingdom from 1918 to 1983. It elected one Member of Parliament (MP) by the first past the post voting system.

The constituency was formed by combining Buteshire (which historically included the islands of Arran, Great Cumbrae and Little Cumbrae) with part of North Ayrshire. The rest of Ayrshire North was merged into Kilmarnock.

In 1918 the constituency consisted of "The county of Bute, inclusive of all burghs, situated therein, and the county district of Northern Ayr, inclusive of all burghs situated therein except insofar as included in the Ayr District of Burghs".

In 1950 some of the constituency was transferred to the then new constituency of Central Ayrshire.

In 1983, Bute and Northern Ayrshire was divided between Argyll and Bute and Cunninghame North.

1918–1950: The county of Bute, and the county district of Northern Ayr, inclusive of all burghs therein except in so far as included in the Ayr District of Burghs.^[2]

1950–1955: The county of Bute, the burghs of Ardrossan, Largs, and Saltcoats, and the district of Saltcoats.^[3]

1955–1983: The county of Bute, the burghs of Ardrossan, Largs, Saltcoats, and Stevenston, and the district of Saltcoats.^[4]

• Former United Kingdom Parliament constituencies