No medieval copies of the French biography (Vie d’Isabelle de France) of Isabelle of France, written by Agnes of Harcourt around 1283, have survived to this day. Our knowledge of this text and its circulation in late medieval France has primarily relied on modern copies and archival evidence. In this article, I present a newly discovered thirteenth-century fragment of the Vie d’Isabelle bound with a manuscript of the Image du monde by Gossuin de Metz (Chantilly, musée Condé, 477). Through a codicological, paleographical, and textual analysis of the two units that constitute this manuscript - the fragment of the Vie d’Isabelle and the complete copy of the Image du monde - I demonstrate that this fragment is the trace of a now-lost manuscript which had been produced in Paris soon after the completion of the Vie d’Isabelle. Chantilly 477, therefore, offers a new piece of evidence for the earliest circulation of Agnes of Harcourt’s text beyond the walls of the abbey of Longchamp.