Antoine was born at Bar-le-Duc, the son of René II, Duke of Lorraine and Philippa of Guelders. He was raised at the court of King Louis XII together with his brother Claude, and also made friends with the Duke of Angoulême, the future King Francis I.

In 1509 he entrusted the reins of the Duchy to his mother and Hugues des Hazards, bishop of Toul, and followed Louis XII in his campaign in northern Italy, where he took part in the Battle of Agnadello of that year. After Louis' death, he went again to Italy under Francis I, participating in the battle of Marignano (14/15 September 1515). However, called back home by problems in Lorraine, he was absent at the decisive battle of Pavia (1525), in which Francis was taken prisoner and his brother François, comte de Lambesc, was killed.

In Lorraine, Antoine had to face the spreading of Protestant Reformation, against which he published an edict on 26 December 1523. The situation worsened the following year, when a rebellion, known as German Peasants' War, broke out in Alsace. The insurrectionists captured Saverne and tried to conquer Saint-Dié, while the peasants of Bitscherland also rose in May 1525. Antoine launched an expedition which reconquered Saverne on 17 May and crushed a peasant army on 20 May near Sélestat. He subsequently promulgated other edicts against the Protestants.

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