Georgiana was born on 1 April 1775, the daughter of St. Leger Aldworth, 1st Viscount Doneraile, and his wife Mary, eldest daughter of Redmond Barry of Ballyclough, Co. Cork. On 15 January 1798 she married Pascoe Grenfell of Taplow House, as his second wife. She died on 12 May 1818. Their eldest son Pascoe St. Leger was born on 5 November 1798; he married firstly Catherine Ann Dupré of Wilton Park, and secondly Penelope Frances Madan, daughter of the Dean of Chichester. He died on 28 March 1870.

Georgiana's father was Member of Parliament for Doneraile in 1749-76, and through his maternal ancestors he succeeded to the estates and assumed the surname and arms of St. Leger. He was created Baron Doneraile of Doneraile, Co. Cork in the Irish peerage on 2 July 1776, and Viscount Doneraile on 22 June 1785.