He was the third but second surviving son of Ernst, Duke of Saxe-Hildburghausen and Princess Sophie of Waldeck-Pyrmont, daughter of German field marshal Prince Georg Friedrich of Waldeck.

When he was sixteen years old, the prince joined the Habsburg Army and became already in 1719 a staff captain in the Infantry Regiment N°18 "Seckendorff", and fought with it in Sicily during the War of the Quadruple Alliance (1717–1720).

In 1737, his attempt to conquer Banja Luka failed, but in practically all important engagements of the war, Joseph displayed personal bravery, for example in the Battle of Grocka (on 22 July 1739), where he covered the retreat of the Imperial Army.

After the outbreak of the Seven Years' War (1756–1763), in the spring of 1757, Joseph was appointed Commander of the Imperial Army, with orders to advance against King Frederick II of Prussia.

In the evaluation by later historians the prince was nearly always blamed for the defeat, although he could hardly have changed the outcome of the fight, because of the catastrophic condition of the Imperial Army and the ineffectiveness of the French troops.

On 13 March 1741 he represented King August III of Poland as godfather of the young Archduke Joseph, the son of the Empress Maria Theresa.

When he died (1780) he left a young heir, the seventeen years old prince Frederick, over whom Joseph took on the role of prince-regent, which he retained until his own death, aged eighty-four.