Scandinavian York (Jórvík) or Viking York (Old Norse: Jórvík) is a term used by historians for what is now Yorkshire during the period of Scandinavian domination from late 9th century until it was annexed and integrated into England after the Norman Conquest; in particular, it is used to refer to York, the city controlled by these kings and earls. The Kingdom of Jórvík was closely associated with the longer-lived Kingdom of Dublin throughout this period.

York was first recorded by Ptolemy around the year 150 as Eborakon. Under the Romans it became the provincial capital and bishopric of Eburacum. The Roman settlement was regularly planned, well defended and contained a stone legionary fortress. The Romans withdrew around 407 and the Anglo-Saxons occupied the settlement from the early 7th century. Post-Roman York was in the kingdom of Deira; it was taken over in 655 by its northern neighbour Bernicia to form the kingdom of Northumbria. The Anglo-Saxon king Edwin of Northumbria was baptized there in 627 and the first Anglo-Saxon archbishop Ecgbert of York consecrated in 780. The settlement became the Anglo-Saxon trading port of Eoforwic.

The Vikings had been raiding the coasts of England from the late 8th century, but in 865 a Viking army landed with the intention of conquering rather than just raiding. The Anglo-Saxon Chronicle described the army as the "mycel heathen here" (Great Heathen Army). They landed in East Anglia where the locals, under Edmund of East Anglia, "made peace" with them in return for horses.

The army, led by Ivar the Boneless and his brother Halfdan Ragnarsson, made its way north to Northumbria where the Anglo-Saxons were embroiled in a civil war. In 862 the ruler of Northumbria, Osberht, had been deposed by Ælla of Northumbria. Ivar the Boneless was able to capitalize on the Anglo-Saxons disarray and captured York in 866/ 867.

After Ivar the Boneless had annexed York, the two Anglo-Saxon leaders settled their differences, they joined forces and attempted to retake the city. When the Northumbrians attacked, the Vikings withdrew behind the crumbling Roman city walls, but the Anglo-Saxon leaders were both killed and the Northumbrians defeated during the ensuing battle on 21 March 867. Symeon of Durham wrote:

In those days, the nation of the Northumbrians had violently expelled from the kingdom the rightful king of their nation, Osbryht by name, and had placed at the head of the kingdom a certain tyrant, named Alla. When the pagans came upon the kingdom, the dissension was allayed by divine counsel and the aid of the nobles. King Osbryht and Alla, having united their forces and formed an army, came to the city of York; on their approach the multitude of the shipmen immediately took flight. The Christians, perceiving their flight and terror, found that they themselves were the stronger party. They fought upon each side with much ferocity, and both kings fell. The rest who escaped made peace with the Danes.

— The Historical Works of Simeon of Durham, Symeon of Durham 1855, p. 470

The remaining Northumbrian leaders, probably led by archbishop, Wulfhere, "made peace" with the Vikings. The Vikings appointed a compliant native prince Ecgberht as puppet ruler of Northumbria. Five years later, in 872, when the Great Army was elsewhere, the local Northumbrians capitalized on their absence by driving Wulfhere and Ecgberht out. The two exiles found refuge at the court of Burgred of Mercia. The revolt was short lived with the Vikings regaining control of York in 873. Wulfhere was recalled to the See but the Anglo-Saxon Ricsige became ruler, as Ecgberht died in 873.