Le Guillou died in 1843 and is buried in Las Tumbas de Le Guillou in Isabel Segunda, Vieques Municipality. The town of Isabel II of Vieques was founded in 1844. His wife Madame Guillermina Ana Susana Poncet died in 1855 and is buried alongside Le Guillou. The cemetery where Le Guillou and his wife are buried was officially named "Las Tumbas de J. J. María le Guillou" by the United States Department of the Interior and was listed in the National Register of Historic Places on August 26, 1994, reference #94000923.