He ascended the throne of Arnor in 777 T.A. after the death of his father Elendur.

He died in 861 T.A.. Eärendur had three sons, who all claimed the throne. To prevent civil war, the Kingdom of Arnor was split in the three parts Arthedain, Cardolan, and Rhudaur. His oldest son Amlaith became the first King of Arthedain.