He had a careful inventory made and a major exhibition was held in 1975. De Peellaert continued to compose music from his boarding school days in Paris onwards. His talent was promoted by the composer and music-theorist Jérôme-Joseph de Momigny, who gave him lessons in piano and harmony. During his stay in Paris, he was a frequent visitor of its lyric theatres. He became an intimate of the Italian composer Ferdinando Paër (1771–1839), the famous author of "Le maître de chapelle". His first compositions were romances and trios for piano, violin, and cello. In 1814, in the family castle "Het Forreyst" in Sint-Andries, he produced a musical comedy called "Crispin Momie". In that same year he wrote a comical one-act opera, which was never produced. He published dozens of romances for piano and vocals, and many operas, ten of which were performed in Brussels, with royalty in the audience. He socialized with most of the important composers and musicians of his time, including "La Malibran", Niccolò Paganini, and Charles Auguste de Bériot, as well as with politicians and aristocrats such as Charles de Brouckère, Edouard Mercier, and Edouard d'Huart. In De Beriot's private theater he frequently accompanied singers on the piano. The orchestral scores of the compositions played in the in Brussels are held in the Brussels city library. He donated his other musical works to the Royal Conservatory in Brussels. Among his compositions can be found:  Besides librettos, de Peellaert also published novels, short stories, and plays.