King is the eldest surviving son of Edward King, 1st Earl of Kingston, and Jane Caulfeild. From 1767 to 1768 he is educated at Eton College. He is styled Viscount Kingsborough between 1768 and 1797. He marries Caroline FitzGerald, daughter of Richard FitzGerald and Margaret King, on December 5, 1769, from whom he later separates. Together they have nine children.
King sits in the Irish House of Commons as the Member of Parliament for Boyle from 1776 to 1783, and for Cork County between 1783 and 1797, and serves as a Governor of County Cork in 1789. In 1797 he succeeds to his father’s titles and assumes his seat in the Irish House of Lords. Between 1797 and his death he is Custos Rotulorum of Roscommon.
On May 18, 1798, King is tried by his peers in the Irish House of Lords after allegedly murdering Colonel Henry FitzGerald. FitzGerald is a married man who elopes with King’s daughter. With public sympathy on King’s side and with considerable publicity he is tried by his peers. An executioner stands beside King with an immense axe, painted black except for two inches of polished steel, and holds at the level of the defendant’s neck. King is acquitted as after three summonses no witnesses come forward. After a short conferee the Lords Temporal returns to the House of Commons and delivers the verdict ‘not guilty.’ The Lord Chancellor of Ireland, John FitzGibbon, 1st Earl of Clare, pronounces the verdict, breaks his wand and dismisses the assembly.
The Directory of the United Irishmen had planned to use the occasion to kill the entire government and all the lords, but one vote cast against this scheme by the informer Francis Magan causes it to be abandoned.
King dies on April 17, 1799 in Rockingham, County Roscommon.
(Pictured: “Robert King, 2nd Earl of Kingston,” pastel by Hugh Douglas Hamilton, RHA (Dublin 1739-1808))