Through his father he was first cousin of Prince Bernhard, consort to Queen Juliana of the Netherlands, and was a guest at their 1937 wedding.

Ernst August married on 3 March 1948 in Oberkassel, Bonn to Christa von Arnim (b.

They had four children: On 30 December 1949 his first cousin Prince Armin succeeded his father Leopold IV as head of the House of Lippe.

Prince Ernst August grew up and lived at Lippesches Palais in Oberkassel, Bonn, which had been home to the Lippe-Biesterfeld family for the past 209 years.

In 1970 he also acquired Syburg castle at Bergen, Middle Franconia, which however he was forced to auction in 1977, followed by the sale of Lippe House in 1979.