The viaduct was built in 1862 as a joint project of the Border Counties Railway and the North British Railway as part of its extension to Riccarton Junction. To obtain the approval of the Duke of Northumberland it had to be built with turrets and battlements, just why is not clear, though it was not without precedent for landowners to request such additions. The two railway companies were amalgamated in 1860.

The railway hoped to tap the coal traffic from Plashetts but this proved disappointing, though there was some traffic from forestry. Passenger traffic was always limited, though the line did open up the North Tyne valley and help to increase the population. The North British Railway now had a route from Edinburgh to Newcastle via Hexham but it compared poorly with the route via Berwick, taking almost five hours for the journey.

The Kielder viaduct was constructed to cross over the North Tyne River as the railway followed its course from the Border Counties Junction, west of Hexham to meet up with the Waverley Route at Riccarton Junction in Scotland. The need to maintain a parallel course up the valley meant that the viaduct had to be skewed with the line of the river. 

This required the construction of complex arches with the stones of the arch gradually changing from aligning with the skew piers to lying at right angles to the line of the bridge at the crown. The system used was devised by Peter Nicholson, a Newcastle mathematician in about 1840, whereby each stone had to be cut and dressed individually. The resulting structure, 130yds long and 55ft high has seven skew arches, and is decorated in baronial style with battlemented parapets and reproduction arrow slits designed to complement the nearby Kielder Castle.  The Kielder viaduct is a fine surviving example of a skew arch bridge, and it remains important part of railway history as there are only about 20 in the UK.

When the line through Kielder closed, to passengers on 15 October 1956, and to freight on 1 September 1958, the viaduct was preserved by the Newcastle and Northumberland Society. It has now been restored and footpaths give access to allow walkers to enjoy the pleasing views from the top of its arches.