Wilhelm was born on 9 August 1749 in Graz in the Duchy of Styria, which was a state in the Holy Roman Empire.

He was the son of Karl Josef Anton, 5th Prince of Auersperg (1720–1800) Countess Maria Josepha Trautson von Falkenstein (1724–1792).

After his grandmother's death in 1726, his grandfather married Countess Maria Franziska Trautson of Falkenstein (a daughter of Prince Johann Leopold Trautson von Falkenstein), with whom he had nine more children, including Joseph Franz von Auersperg, Prince-Bishop of Passau.

Following the dissolution of the Holy Roman Empire in 1806, the Imperial State of Auersperg was mediatised to the Grand Duchy of Baden.

[7] Together, they were the parents of: The Prince died on 16 March 1822 in Sopron in the Kingdom of Hungary on the Austrian border, near Lake Neusiedl.