Wilhelmine Christine was born in 1629[1][note 1] as the youngest daughter of Count William of Nassau-Siegen and Countess Christiane of Erbach.

[1][3][4][5] The exact date and place of birth of Wilhelmine Christine are unknown; she was baptised on 10 June 1629 in Heusden,[2][3][4][6] the city of which her father had been governor since 1626.

[7][8] Count William Frederick of Nassau-Diez, the stadtholder of Friesland, noted in June 1645 in his diary that the sixteen-year-old Wilhelmine Christine was the favourite girlfriend of Prince William II of Orange, "die hij zoo dicwils custe als hij woude, alleen sijnde, en de borstjes tastede" ("whom he kissed as much as he wished, being alone, and touching the breasts").

William II had to promise Wilhelmine Christine "sich deechlijck te hauden" ("to stay decent"), but the consequence of this intimacy was that her mother Christiane did not want Wilhelmine Christine to be alone with Prince William, "doch dat sie het allebeide sochten" ("but that they both sought it").

[11] Wilhelmine Christine married at Arolsen Castle on 26 January 1660[1][note 2][5] to Count Josias II of Waldeck-Wildungen (Wildungen,[3][4][6] 31 July 1636Jul.