He was the eldest son of Robert Uniacke (afterwards Fitzgerald) of Corkbeg and descended from the Munster Desmond FitzGerald Knights of Glin and Kerry, through Sir Garrett FitzGerald Knt of Lisquinlan and Sir Robert Tynte of Youghal and Ballycrenane. His younger brother was the infamous 1798 United Irish Rebellion Tipperary High Sheriff Col Sir Thomas Judkin-Fitzgerald, 1st Baronet of Lisheen, Co Tipperary. He was educated in the law at the Middle Temple.