| Ernest Frederick I | |
| Succession: | Duke of Saxe-Hildburghausen |
| Reign: | 1715–1724 |
| Predecessor: | Ernest |
| Successor: | Ernest Frederick II |
| Spouse: | Countess Sophia Albertine of Erbach-Erbach |
| Issue: | Ernest Frederick II Prince Ludwig Frederick Elisabeth Albertine, Princess of Mirow |
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| Issue-Pipe: | among others... |
| House: | Saxe-Hildburghausen |
| Father: | Ernest, Duke of Saxe-Hildburghausen |
| Mother: | Countess Sophie Henriette of Waldeck |
| Birth Date: | 21 August 1681 |
| Birth Place: | Gotha |
| Death Place: | Hildburghausen |
| Religion: | Lutheranism |
Ernest Frederick I, Duke of Saxe-Hildburghausen (21 August 1681 in Gotha – 9 March 1724 in Hildburghausen), was a duke of Saxe-Hildburghausen.
He was the eldest son of Ernest, Duke of Saxe-Hildburghausen and Countess Sophie Henriette of Waldeck.
During his youth he served on the Netherlands in the imperial military army, during which he was wounded in the Spanish Succession War at Höchstädt; in 1715 he left the Army after the death of his father, and assumed the government of the duchy of Saxe-Hildburghausen.
He wanted, like many German princes, to repeat the splendor of the court of the King Louis XIV of France in his own duchy; but this was the cause of his financial ruin.
Constantly in need of money, he levied taxes and sold towns. Among them was the county of Cuylenburg, the dowry of his wife. The county was sold in 1720 to the General States, not for the repayment of the debts but to build in his palace a garden connected with a channel. Likewise, in 1723 the office was finally sold to the duchy of Saxe-Meiningen. But the sale, without the assent of his wife was illegal, and this led to a war with Saxe-Meiningen. The county was occupied with troops of both duchies and at the end of the war all of the county was devastated and ruined.
Because of his intolerable fiscal charges, in 1717 an open revolt developed in the duchy.
In Erbach on 4 February 1704, Ernest Frederick married Countess Sophia Albertine of Erbach-Erbach. They had fourteen children: