John was born in 1643 in Dublin, the sixth child of James Butler and his wife Elizabeth Preston.
[b] John was born in Dublin where his mother had rejoined his father in 1642 after the Confederates allowed her to leave Kilkenny Castle.
On 20 August 1662, during the Irish Parliament (1661–1666), the only one held in the reign of Charles II (1660–1685), John replaced his brother Thomas as the member (MP) for Trinity College as Thomas had been summoned to the House of Lords by a writ of acceleration as Earl of Ossory and could therefore not sit any more in the House of Commons.
[8] In 1671 John, together with his cousin Anthony Hamilton, saved Dublin Castle from destruction by fire.
[12] On 13 April 1676, John was created Baron Aghrim, Viscount Clonmore, and Earl of Gowran, all in the peerage of Ireland.