Son of Aragorn and Arwen. Eldarion's date of birth is not known. He was the only son and heir of Aragorn, King Elessar. Eldarion had several sisters whose names are not known.

In the year 120 of the Fourth Age, Aragorn perceived that his life was coming to an end and that his son was ready to assume kingship of Gondor and Arnor. Eldarion accompanied his father to the House of Kings in the Silent Street and received the Winged Crown of Gondor and the Sceptre of Arnor from him. Then Eldarion said goodbye to his father and Aragorn died. Eldarion's mother Arwen then bid him farewell and went to Lothlorien where she died a year later.

Eldarion was the second King of the Reunited Kingdom. According to one source, he may have ruled until at least the year 220 of the Fourth Age. It was foretold that Eldarion's realm would be great and that it would endure under the rule of his descendants for a hundred generations of Men.