In 1633 he joined the Dutch army where he worked in the headquarters in Maastricht.
Subsequently, he joined the Dominican Order where he adapted his first name Jean-Baptiste.
He is the author of several works about the Antilles where he described the indigenous peoples, the animals, and the plant world, including Histoire générale des îles Saint-Christophe, de la Guadeloupe, de la Martinique et autres de l'Amérique (Paris, 1654), Histoire naturelle et morale des îles Antilles de l'Amérique avec un vocabulaire caraïbe (1658), La Vie de Sainte Austreberte (1659) and l'Histoire générale des Antilles habitées par les Français (four volumes, 1667–1671).
Particularly in his last work Du Tertre created the myth of the "Bon Sauvage" where he placed "the virtuousness of the heathen Caribs above the immoral life of the Europeans".
Du Tertre was the first who described the yellow fever when several epidemics burst over Guadeloupe and Saint Christopher in 1635, 1640, 1648 and 1667.