He was the son of Maurice FitzGerald, 1st Earl of Desmond, by his third wife Aveline (Eleanor), daughter of Nicholas FitzMaurice, 3rd Lord of Kerry.

He married, by the King's command, Eleanor, daughter of James, 2nd Earl of Ormond, who brought with her as her portion the barony of Inchiquin in Imokelly.

O'Donovan quotes the following concerning his character: 'A nobleman of wonderful bountie, mirth, cheerfulness in conversation, charitable in his deeds, easy of access, a witty and ingenious composer of Irish poetry, and a learned and profound chronicler; and, in fine, one of the English nobility that had Irish learning and professors thereof in greatest reverence of all the English in Ireland, died penitently after receipt of the sacraments of the holy church in proper form.'

[5] While in prison, Gerald wrote poetry in Irish, most famously the poem Mairg adeir olc ris na mnáibh (Speak not ill of womankind).

[1] Also an accomplished poet in Norman French,[2] Gerald was instrumental in the move by the Desmond Geraldines towards greater use of the Irish language.

After his disappearance in 1398, another legend grew up that Gerald sleeps in a cave beside (or under) Lough Gur,[1][9] and will someday awaken and ride forth on a silver-shod steed to rule again in Desmond,[1] – one of the many worldwide versions of the King asleep in mountain mythologisation of heroes.