The Kilsyth and Bonnybridge Railway was a railway line in central Scotland, built to exploit the mineral extractive industries in the area; it opened in 1888. A passenger service was run, but bus competition overwhelmed it after 1920 and the passenger service closed in 1935. The goods and mineral traffic continued, but it was dependent on the industries it served, and when they declined so did the business on the railway; it closed in 1964 and none of it is now in railway use.
Kilsyth and Bonnybridge had both become important industrial centres during the nineteenth century; the proximity of the Forth and Clyde Canal as a transport medium facilitated the development of industry, and coal mining and iron smelting had become particularly dominant. The Baird Brothers of Gartsherrie were especially prominent in Kilsyth, and they built a considerable network of mineral tramways serving their pits and ironworks.
Although the Edinburgh and Glasgow Railway had opened in 1842, its route lay some distance to the south, and across the Forth and Clyde Canal. The first town in the district reached by a railway was Denny, served from the east in 1858: the Scottish Central Railway opened its branch to the town, from Larbert Junction.
In 1878 the nominally independent Kelvin Valley Railway was opened, running from Kilsyth to a junction with the Campsie Branch of the North British Railway, successor to the Edinburgh and Glasgow Railway, and giving access for passengers and minerals to Glasgow over that company's lines. The following year a second section of the Kelvin Valley line was opened, running to Maryhill on the north-west margin of Glasgow, and giving access there over the Stobcross branch of the North British Railway to the new dock at Stobcross, soon to be named the Queen's Dock.
The industrial potential of the tract of land between Kilsyth and Denny was attractive for exploitation. At this period there was intense rivalry between the North British Railway and the Caledonian Railway, and any proposed construction into the competitor's territory might result in hostile and costly reprisals. At length an independent concern was promoted to build a line closing the gap.
The Kilsyth and Bonnybridge Railway was authorised by Act of Parliament on 10 August 1882, with capital of £130,000. The line was to run from the Kelvin Valley Railway at Kilsyth to Bonnywater Junction on the Caledonian's Denny branch.