He was born in Meiningen, the eldest son of the heir apparent to the duchy of Saxe-Meiningen, Prince Georg and his second wife, HSH Princess Feodora of Hohenlohe-Langenburg.

Not permitted to share her husband's dynastic title, his wife was created Baroness von Saalfeld on their wedding day by Ernst's father, Georg II.

[1] Despite his unequal marriage, Ernst retained his succession rights to the duchy of Saxe-Meiningen.

[2] When his older half-brother, the last reigning duke of Saxe-Meiningen, Bernhard III, died on 16 January 1928, Ernst succeeded him as head of the ducal house, but never reigned, since the monarchy was abolished at the end of World War I in 1918.

Rather than his own son, Ernst's nephew Georg, Prince of Saxe-Meiningen, succeeded him as head of the house following his death at Schloss Altenstein.