She was the third of five daughters of King Frederick III of Denmark and Sophie Amalie of Brunswick-Lüneburg.

[1] Wilhelmina Ernestine was betrothed at Sophie Amalienborg Palace in Denmark in the presence of Charles on 24 June 1671.

On 14 August, Wilhelmina Ernestine left Denmark with a large Danish retinue for Heidelberg, where the wedding ceremony was conducted on 20 September 1671.

Wilhelmina Ernestine was granted a large dowry from Denmark, and she also received the towns of Germersheim and Oppenheim from her father-in-law, Elector Charles I Louis.

Wilhelmina Ernestine is not noted to have had any particular interests, she preferred solitude and a reclusive quiet life style in contrast to the active social life preferred by Charles, and she reportedly offended him by her pride over her royal status.