Domhnall Mac Briain was the son of Brian Boru, the High king of Ireland and Eacraidh whose father was a Rí of a tuath in Mide. He had two known siblings, one brother (Tadc) and a sister. The Annals of Inisfallen record that he raided Cenél Conaill. Half of the army was led by Domhnall, while the other half by his half brother Murchad mac Briain.^{[citation needed]}

He died in 1012 due to natural causes. He had no children.^{[1]: 202 [1]: 283 [2][3]}