FitzGerald was the eldest surviving son of William FitzGerald, 2nd Duke of Leinster and his wife, Emilia Olivia St George, daughter of the 1st Baron St George.

In 1831, he was admitted to the Privy Council of Ireland and to the Privy Council of Great Britain and was Lord High Constable of Ireland at the coronations of William IV and Queen Victoria.

Marc Bédarride's Rite of Misraim was imported from France to Ireland during the time of FitzGerald.

One of the Bédarride brothers is supposed to have visited Ireland in 1820 and by February 1821, a council of seventeen members of the Rite was formed, including; FitzGerald, Fowler, Dumoulin, Norman, Mitchell, Trim and Jamar (a Frenchman residing in Dublin).

Banned in France by the government in 1822, it continued to exist in Ireland as part of the Supreme Grand Council of Rites (approved by the Grand Lodge of Ireland), set up on 28 January 1838.