This preserved railway runs for about one mile in total alongside the Bristol Floating Harbour from near the "SS Great Britain" historic ship to the M Shed Museum, with a branch alongside the River Avon new cut.  The harbour railway network first opened in 1872 as a joint venture between the Great Western Railway and the Bristol & Exeter Railway.  The latter was eventually absorbed by the GWR.  The original connection to the main line tracks was at Temple Meads, but later there was a connection to the Portishead line.

The connection to Temple Meads closed in 1964, when the harbour was running down, and shipping was docking at the developing Avonmouth.  The Western Fuel Company continued operations there until 1987.  Meanwhile, the Bristol Harbour Railway was established as a tourist attraction in 1978.  It is operated by the Bristol Museums Service, and until 2009 was part of the Bristol Industrial Museum at the harbour.  In 2011 a redeveloped museum called "M Shed" was established, replacing the original, and the railway is now part of that.  It operates on one or two weekends each month except in winter.