On 30 October 1665 he was summoned to the Irish House of Lords by writ of acceleration as Baron Ardee.
Between 1671 and his death he was Custos Rotulorum of County Dublin.
He was a captain in Sir Arthur Forbes's Regiment of Horse in 1672.
In 1674 he was made a member of the Privy Council of Ireland and in 1675 he succeeded to his father's title as Earl of Meath.
He was succeeded in his title by his brother, Edward Brabazon.