He was born Étienne de Grellet du Mabillier in Limoges, the son of a counsellor of King Louis XVI. Raised as a Roman Catholic, he was educated at the Military College of Lyons, now the Institut d'études politiques de Lyon, and at the age of 17 he entered the personal guard of the king. During the French Revolution he was sentenced to be executed, but escaped and eventually fled Europe to the United States in 1795.
Impressed by the writings of William Penn, George Fox, and Quaker beliefs, in 1796 Grellet joined the Society of Friends. He became involved in extensive missionary work across North America and most of the countries of Europe, in prisons and hospitals, and was respectfully granted meetings with many rulers and dignitaries, including Pope Pius VII, Czar Alexander I, and the Kings of Spain and Prussia. He encouraged many reforms in educational policies and in hospital and prison conditions.
In 1804 Grellet married Rebecca Collins, the daughter of the publisher Isaac Collins. The family home, the Isaac Collins House, in Burlington, New Jersey, is now listed on the National Register of Historic Places.
Grellet died in Burlington on 16 November 1855 and his body was buried there, behind the Quaker Meeting House at 340 High Street.
- Benjamin Seebohm: Memoirs of the life and gospel labours of Stephen Grellet, Longstreth, Philadelphia, 1862 (3rd ed.), 426+438 p.
- Frances Anne Budge : A missionary life : Stephen Grellet, Nisbet, London, 1888, 127 p.
- William Guest : Stephen Grellet, Headley, London, 1903, 226 p.
- William Wistar Comfort, 'Stephen Grellet, 1773-1855', MacMillan, New York, 1942, 202p.
- Claus Bernet (2007). "Grellet, Stephen". In Bautz, Traugott. Biographisch-Bibliographisches Kirchenlexikon (BBKL) (in German). 28. Nordhausen: Bautz. cols. 687–690. ISBN 978-3-88309-413-7.