A Tory, he served in the governments of Lord Wellington and Robert Peel, but is best known for his defeat in the 1828 Clare by-election, hastening Catholic Emancipation across Britain and Ireland.

He tried to make the Swedish King, Charles XIV John, repay the large sums of money given to him during the Napoleonic Wars, but this was to no avail and he returned to Britain in 1823.

The election was noteworthy in terms of Irish history because it led directly to Catholic Emancipation spearheaded by his successor, Daniel O'Connell as a result of his win.

However, in 1835 he was created Baron FitzGerald, of Desmond and of Clan Gibbon in the County of Cork, in the Peerage of the United Kingdom, and was able to take a seat in the House of Lords.

Apart from his political career FitzGerald was Lord Lieutenant of County Clare from 1831 to 1843, a trustee of the British Museum, President of the Institute of Irish Architects and a Fellow of the Society of Antiquaries.