Born in Nevy, France, Gabet was ordained in 1833 and entered the Vincentians in 1834. He went to Macao in 1835 and Mongolia in 1837, took part in a scientific expedition to Tibet from 1844 to 1846, and then returned to Europe. He is regarded as the founder of the modern Catholic mission to the Mongols. He became more widely known through the two-volume report published by his confrere E. R. Huc, Souvenir d'un voyage dans la Tartarie et le Tibet (1851).
His memorandum presented to the Holy See and Propaganda Fide, entitled "Reseignements sur l'etat des missions en Chine," which he soon afterward published in Coup d'oeil sur l'dtat des missions de Chine presente au Saint Pere, le Pape Pie IX (1848), got a mixed reception. Apart from the very realistic description of the missionary situation in China, his unambiguous demand for a Chinese clergy caused offense. In 1850 E. J. F. Verrolles, the vicar apostolic of Manchuria, succeeded in getting the memorandum formally condemned by Propaganda Fide. After submitting a report in Rome, Gabet went to Brazil (1849), where he left the order. He died in Rio de Janeiro.