O'Neill survived his brother earl eight years, having made various attempts to induce the King of Spain to aid him in the recovery of his patrimony.
He died in 1616, in the seventy-sixth year of his age.

Sir Francis Cottington, announcing the event from Madrid, said, 'The Earl of Tyrone is dead at Rome; by whose death this king saves 500 ducats every month, for so much pension he had from here, well paid him.
Upon the news of his death, I observed that all the principal Irish entertained in several parts of this kingdom are repaired unto this court.'.