Elizabeth was the eldest child of the Duke Eric I of Brunswick-Calenberg and his wife Elisabeth (1510-1558), the daughter of Elector Joachim I of Brandenburg.
Elisabeth married on 19 August 1543 in Münden to Count George Ernest of Henneberg (1511-1583).
His brother Poppo XII had married Elisabeth's mother two years earlier.
[2] Via his marriage to Elisabeth, George Ernest came into contact with the leading Protestant dynasties in Germany.
As a strictly evangelical countess consort, she played a decisive rôle in converting the county of Henneberg to Protestantism.