Eysteinsson is a Scandinavian surname. Notable people with the surname include:
Halfdan Eysteinsson, the subject of Hálfdanar saga Eysteinssonar, a legendary saga from early 14th century IcelandRognvald Eysteinsson, founder of the Earldom of Orkney in the Norse SagasSigtryg Eysteinsson, king of the Norwegian petty kingdoms Raumarike and Hedmark in the 9th centurySigurd Eysteinsson (aka Sigurd the Mighty, ruled circa 875–892), the second Viking Earl of Orkney