After obtaining the Abitur in 1891, he served as an officer in the German Army until 1894, when he left to study political science at the universities of Bonn and Berlin.

Leopold was confirmed as Prince of Lippe and Alexander's successor on 25 October 1905, following a court ruling.

On 24 February 1916, Bernhard and his brother were upgraded to the title Prince of Lippe-Biesterfeld with the style Serene Highness.

Just three days after upgrading the titles of members of the Lippe-Weissenfeld line, and following the German Empire's defeat in World War I and the subsequent revolution, Leopold was forced to renounce the throne on 12 November 1918.

So in 1947 when Leopold wrote his will, Armin, his youngest son and only child with his second wife, would succeed him as head of the House of Lippe and also become administrator of the princely family's properties such as Schloss Detmold.