Viret studied as a scholar in his hometown school and then attended the University of Paris, where he was converted to the Reformed faith. He returned to Orbe in 1531 to escape the persecutions in Paris.
William Farel, a Protestant preacher, called Viret to the ministry at his return to Orbe. On 6 May 1531 Viret preached his first sermon, being only twenty years old at the time. His preaching was received with astonishment and acclamation by his hearers, and many were soon converted to the Reformed Faith, among them both Viret's parents. Subsequently, he preached in Lausanne and Geneva, before undertaking missionary tours in France, preaching to crowds of thousands in Paris, Orléans, Avignon, Montauban, and Montpellier. His preaching was sweet and winning, and won him the name of "The Smile of the Reformation."
At one time he was captured by Catholic forces. Viret was considered one of the most popular French-speaking preachers in the 16th century. Above all he was the reformer of the city of Lausanne, where he converted the local population to the Reformed faith. In his time, Lausanne also became, with Geneva, a training ground for Reformation preachers. Among those who studied in Lausanne was the author of the Belgic Confession, Guy de Brès. While at Lausanne, Viret founded a Reformed Academy, which was forced to relocate to Geneva in 1559. The relocated professors and students of Viret's Lausanne Academy soon became the foundation of Calvin’s famed Geneva Academy.
For health reasons Viret left Geneva and moved to Southern France where we preached among the Huguenots. He died in Orthez France in 1571.