He was the third but eldest surviving son of Ernst Frederick I, Duke of Saxe-Hildburghausen and Countess Sophia Albertine of Erbach-Erbach.

As a result, his mother, the Dowager Duchess Sophia Albertine, acted as a regent on his behalf until he reached adulthood five years later.

In 1743 he received an Infantry Regiment from Charles Theodore, Elector of Bavaria as a Lieutenant-General.

In the meantime, the indebtedness of the duchy had become so high that total public revenues did not even cover the interest.

In Fürstenau on 19 June 1726 Ernst Frederick married Caroline of Erbach-Fürstenau (d. July 1745).