René succeeded his father in Vaudémont in 1470 and, three years later, his uncle as captain of Angers, seneschal and governor of Anjou.

That same year he became Duke of Lorraine, which was at the time under the pressure of both Louis XI of France and Charles the Bold of Burgundy, with whom he initially allied.

With this force René defeated and killed Charles at the Battle of Nancy (5 January 1477), ending the Burgundian Wars.

Likewise, any authority over Luxembourg was merely theoretical outside of the seizure of Virton,[6] as the Duchy remained in possession of the Habsburgs throughout René's lifetime.

In 1484 Peter II, Duke of Bourbon, regent for the young King Charles VIII of France, formally installed him in the Duchy of Bar.

In 1482, René traveled to Italy and defeated the Duke of Ferrara in the Battle of Adria as an ally of the Republic of Venice.