The fossilised artefact, said to date from the Pleistocene period – making it at least 120,000 years old – was uncovered in the cliffs at Reighton Sands beach.
The walrus is believed to have originated from Doggerland, an area of land which once connected the UK to mainland Europe. It was submerged by rising sea levels around 6,500 BC.
It has been donated to the Rotunda museum at Scarborough by Haven Holidays, present-day owners of Reighton Sands, and will form part of two-year exhibition from this weekend.
Jennifer Dunne, collections manager for the Scarborough Museums Trust, said the skull was a “rare and hugely significant” find.
“We’re at the very beginning of a journey to find out more about this walrus, which is the first of its kind to be found in situ,” she said.
“This fossil holds great potential for unlocking more secrets about these creatures that were once found on Doggerland and the prehistoric coastlines of Europe.”
Scientists believe that walruses were living in the North Sea between 60,000 and 90,000 years ago but this theory is still being debated.