The woman was named locally as Vanessa Cabban, an author and illustrator.
A British Transport Police spokesman said: “Our officers were called to the line at Goswick shortly before 3pm on Wednesday, 17 December, after reports a person had been hit by a train.
“Colleagues from Northumbria Police, North East Ambulance Service and Northumberland Fire and Rescue Service also attended, but a 43-year-old woman from Tweedmouth was pronounced dead at the scene.
“We are not treating the death as suspicious, but will prepare a file for the coroner.”
The incident happened at about 2.45pm. The woman was struck by an Edinburgh to London service.
The incident caused delays to trains between Newcastle and Edinburgh via Morpeth.