Johann Adolf was the youngest son of Frederick II, Duke of Saxe-Gotha-Altenburg and Magdalene Augusta of Anhalt-Zerbst.

On his Grand Tour in 1741 he visited France als later his sister Augusta in the United Kingdom where he also obtained a Ph.D. from the University of Oxford.

After Prince Joseph of Saxe-Hildburghausen died in 1787 he became Elder of the Ernestine line of the House of Wettin, a position already hold by his older brother Frederick III until his death in 1772.

After Johann Adolf died in 1799 Prince Josias of Saxe-Coburg-Saalfeld became Elder of Ernestine Wettin and received the Oldisleben territory.

[5] Johann Adolf later married Marie Maximiliane Elisabeth Schauer (25 October 1732 – 31 January 1779) morganatically.