[1] Born in Paris, he died in Carlsbourg in the Walloon Region of Belgium.

Jules was the oldest son of Hercule Mériadec, Prince of Guéméné (1688–1757) and Louise Gabrielle Julie de Rohan (1704–1741).

On 10 February 1743 he married Marie Louise de La Tour d'Auvergne (1725–1793), daughter of Charles Godefroy de La Tour d'Auvergne, Duke of Bouillon and Maria Karolina Sobieska.

Together, Jules and Marie Louise had one son: The Prince of Guéméné died in Belgium in 1788.

[2] His son, daughter-in-law, and grandchildren fled to Bohemia before the French Revolution.