The surname originates with Gilbert (Gibbon) FitzJohn, who was an illegitimate son of John FitzThomas, 1st Baron Desmond (died 1261); the line of Anglo-Norman aristocracy in Ireland descended from Gilbert became known as Fitzgibbon.

[1] Fitzgibbon means "son of Gibbon", derived from Norman French fiz/fitz (meaning "son") and Gibbon (a Norman French affectionate form of the name Gilbert).

[2] The Fitzgibbon families of the present day are to be found concentrated in the parts of the Ireland in which they originated.

Their territory prior to the upheaval of the 17th century was the south-eastern corner of Co.

The best known of the Fitzgibbons was John 'Black Jack' Fitzgibbon (1749–1802), Lord Chancellor of Ireland, whose pro-English and anti-Catholic activity at the time of the Acts of Union made him hated in his own day and his memory reviled since.