As Mademoiselle Lange, Jeanne immediately became a sensation in Paris, building up a large aristocratic clientele. The dashing Maréchal de Richelieu became one of her recurring customers. Because of this, Jean du Barry saw her as a means of influence with Louis XV, who became aware of her in 1768 while she was on an errand at Versailles. The errand involved the duc de Choiseul, who found her rather ordinary, in contrast to what most other men thought of her. In any case, Jeanne could not qualify as an official royal mistress unless she had a title; this was solved by her marriage on 1 September 1768 to du Barry's brother, comte Guillaume du Barry. The marriage ceremony included a false birth certificate created by Jean du Barry himself, making Jeanne younger by three years and of nobler descent.
For now, Jeanne was installed below the King's quarters in Lebel's former rooms. She lived a lonely life, not able to be seen with the King since no formal presentation had taken place.