The Ardrossan Railway began as a wagonway, built by the Glasgow, Paisley and Johnstone Canal company, which opened in 1831 between Ardrossan and Kilwinning and was known as the Ardrossan and Johnstone Railway. It was initially built to the Scotch gauge of 4 ft. 6 in. and was worked by horses. There was a single passenger carriage that held 24 passengers – 16 inside and 8 outside. It commenced on the west side of Ardrossan harbour and was intended to terminate at Johnstone, to connect with the Glasgow, Paisley and Johnstone Canal. However, owing to lack of funds it was forced to terminate at Kilwinning. In 1840 the line was converted to 4 ft. 8½ in. gauge and connected with the Glasgow, Paisley, Kilmarnock and Ayr Railway at Kilwinning station; in 1854 it merged with the recently formed Glasgow and South Western Railway.
The extension from Ardrossan to Largs was built by the G&SWR and opened in stages. Service from Ardrossan to West Kilbride began on 1 May 1878, between West Kilbride and Fairlie on 1 June 1880, and between Fairlie and Largs on 1 June 1885. The Largs Branch is now part of the Ayrshire Coast Line and electric service on the 25 kV AC overhead system was introduced on 19 January 1987.