Jean Alphonse Turretin (August 1671 – May 1737) was a Swiss theologian.
The son of Francis Turretin, he was born at Geneva. He studied theology at Geneva under Louis Tronchin, and after travelling in Holland, England and France was received into the "Venerable Compagnie des Pasteurs" of Geneva in 1693. Here he became pastor of the Italian congregation, and in 1697 professor of church history, and later (1705) of theology.
During the next forty years of his life he enjoyed great influence in Geneva as the advocate of a more liberal theology than had prevailed under the preceding generation, and it was largely through his instrumentality that the rule obliging ministers to subscribe to the Helvetic Consensus was abolished in 1706, and the Consensus itself renounced in 1725. He also wrote and labored for the promotion of union between the Reformed and Lutheran Churches, his most important work in this connection being Nubes testium pro moderate et pacifico de rebus theologicis judicio, et instituenda inter Protestantes concordia (Geneva, 1729). Besides this he wrote Cogitationes et dissertationes theologicae, on the principles of natural and revealed religion (2 vols., Geneva, 1737; in French, Traité de la verité de la religion chrétienne) and commentaries on Thessalonians and Romans.