Ernest Augustus nació el 17 de noviembre de 1887 en Viena, Austria-Hungría (ahora Austria). Estuvo casado con Viktoria Luise von Preußen. Murió el 30 de enero de 1953 en Baja Sajonia, Alemania.
He lived to see one of his children become a consort to a monarch - in 1947 his daughter Frederica became Queen of the Hellenes when her husband Prince Paul of Greece and Denmark succeeded his brother as King. The Duke of Brunswick is also the maternal grandfather of Queen Sophia of Spain and the former King Constantine II of Greece.