Rohan-Chabot was born in Paris on 29 February 1788. He was the eldest son of Alexandre-Louis-Auguste de Rohan-Chabot and Anne Louise Élisabeth de Montmorency (1771–1828). Among his younger siblings were Fernand de Rohan-Chabot, Adélaïde de Rohan-Chabot (who married Aimé Charles de Gontaut-Biron, Marquis de Saint-Blancard), Marie-Charlotte-Léontine de Rohan-Chabot (who married Antoine de Lambertye, Marquis of Gerbéviller), Anne-Louise-Emma-Zoë-Clementine de Rohan-Chabot (who married Count Joseph d'Estourmel), and Louis Charles Philippe Henri de Rohan-Chabot (who married Marie-Caroline de Biencourt).[2]
After the death of his wife, he devoted himself to the church, entering the Saint-Sulpice Seminary in Paris, from 1819 until 1822. When he entered religious orders, his younger brother, Fernand, took the title, Prince of Léon. He was ordained on 1 June 1822, and preached at La Roche-Guyon before becoming Vicar General of Paris.[4]
On 2 May 1808, Louis-François married Marie Georgine Armandine de Sérent, a granddaughter of the Duke of Sérent. After her death from a fire on 10 January 1815, he devoted himself to the church.