He was the second son of an unknown Lord Dayne. He spent his youth being taught the art of arms at Starfall, and was eventually deemed worthy of wielding Dawn, the ancestral blade of House Dayne. He was the older brother of Ashara Dayne and Allyria Dayne, and the uncle of Edric Dayne.
He was absent for much of Robert's Rebellion, but would eventually fight Eddard Stark at the Tower of Joy, and would have killed him had it not been for Howland Reed. Ser Arthur Dayne perished, and Lord Stark would return Dawn to Starfall out of honour for his opponent. Arthur's body was buried under a cairn made up of rocks from the Tower itself, along with his brothers, as well as Ned's companions.