1. He was the fourth of five children (one died in childbirth) of John Michaelis Barnardo, a furrier who was of Sephardic Jewish descent, and his second wife, Abigail, an Englishwoman and member of the Plymouth Brethren.

Barnardo war das erste von fünf Kindern (eines starb bei der Geburt) des Kürschners John Michaelis Barnardo und dessen zweiter Frau Abigail, einer Engländerin, die Mitglied der Plymouth Brethren war.