His parents were Henry, Prince of Nassau-Dillenburg (1641–1701) and his wife Princess Dorothea Elisabeth of Legnica-Brzeg (1646–1691).
Around 1694 he made his grand tour which took him through Germany, the Netherlands, England, Denmark, Sweden and Italy.
Negotiations dragged on until 1717; William II received Mengerskirchen, Lahr in the Westerwald, and Frickhofen.
In 1709, he was appointed Knight of the Order of Saint Hubert, which had been revived by Elector Palatine John William in September 1708.
He married on 13 January 1699 in Harzgerode to Johanna Dorothea (24 December 1676 – 29 November 1727), the daughter of Duke Augustus of Schleswig-Holstein-Sonderburg-Plön-Norburg.