It opened on 5 August 1850 to both freight and passenger traffic; passenger operations included direct Newcastle to Alnwick services, as well as regular shuttle runs between Alnmouth and Alnwick. As late as 1966, some of the Alnmouth to Alnwick shuttles were operated by steam locomotives.
It was closed in January 1968 on cost grounds. The old embankment after the line had crossed the A1 road now forms the rear boundary of some of the gardens on the Royal Oak Gardens residential development.
The Aln Valley Railway Trust is reopening the old branch line in stages from a new terminus station in Alnwick back to Alnmouth. The first stage is almost complete with the construction of the new Alnwick Lionheart Station, made necessary by the unavailability of the original site and new buildings on some of the trackbed into the town centre.
Planning permission was granted by Northumberland County Council on 1 July 2010, the lease for the site signed on 22 Feb 2012 and the site opened to visitors on 14 July (just 5 months later). The first train (an engineer's train) ran on 3 Nov 2012.
The new site opened to visitors in the summer of 2012 to demonstrate the ongoing work alongside exhibits of rolling stock as well as an indoor exhibition area, cafe, souvenir shop and model railway. The first operating season followed in 2013 culminating in the first trial steam service on 10 September. The railway was formally opened by the Duke of Northumberland on 30 October 2013.
The new "Alnwick Lionheart" station site at Alnwick is on a different site from the original Alnwick station due to the A1 dual carriageway being built across the original trackbed after the 1968 closure. Between April 2000 and November 2014 the Aln Valley Railway also had a presence at Longhoughton goods yard, used for the temporary storage of stock and preparation work prior to obtaining the Lionheart Site.
Butt, R. V. J. (1995). The Directory of Railway Stations: details every public and private passenger station, halt, platform and stopping place, past and present (1st ed.). Sparkford: Patrick Stephens Ltd. ISBN1-8526-0508-1. OCLC60251199.