The North Eastern Railway Company was formed in 1854 when the York, Newcastle and Berwick, York and North Midland, Leeds Northern, and Malton and Driffield Railways amalgamated. It acquired the West Hartlepool Railway in 1864, the Stockton and Darlington in 1865 and the Blyth and Tyne in 1874. As a result it almost had a monopoly in its area. Its area of operation covered the north east and north Yorkshire, and stretched from Berwick-on-Tweed south to Doncaster, with extensions into Westmorland and Cumberland and into Scotland. It exercised running powers over the North British line from Berwick to Edinburgh and a joint owner of the Forth Bridge. It was also a joint owner of the East Coast Joint Stock with the Great Northern and North British Railways.

Its main goods traffic was coal from the Northumberland and Durham coalfields. It was an early investor in electrification, initially to deal with a difficult approach to the docks but later extended to the Newcastle-upon-Tyne suburban area. It also electrified goods workings between Shildon and Middlesbrough and planned to electrify the York to Newcastle route (even building a prototype locomotive) but the first world war intervened and the work was not carried out.

The headquarters of the NER were in York where it also had its carriage works. The main works were at Shildon. Among its Chief Mechanical Engineers were Wilson Worsdell, Thomas Worsdell and Vincent Raven.

The NER became part of the London and North Eastern Railway under Grouping in 1923.