January 1511), daughter of Bruno VII (IX), the last lord (Herr) of Querfurt, and his wife Brigitte zu Stolberg (1468–1518).
Ernest's second marriage was to Dorothea, Countess at Solms-Lich (25 January 1493 - 8 June 1578, Mansfeld), daughter of Philip, Count of Solms-Lich (1468) and his wife Adriana von Hanau-Münzenberg (1470–1524).
Two of his children by his second marriage were the military commander Peter Ernst I von Mansfeld-Vorderort (1517-1604) and Elisabeth (ca.
1516–1541), briefly wife of Frederick, Hereditary Prince of Saxony.
He is an ancestor of the Brazilian imperial family by the Empress Maria Leopoldina of Brazil.