Entering the army at the age of fourteen as proprietary colonel of an infantry regiment, he shared in almost all the exploits of the French arms during the reign of Louis XIII. He took part in the siege of La Rochelle, survived the defence of the island of Re against the attacks of the English under the Duke of Buckingham, and accompanied the French forces to Italy in 1629.
In 1630 he became the French ambassador to the court of Duke Victor Amadeus I of Savoy, and engaged in diplomatic and administrative work in Italy until 1635, when war broke out between France and Spain. In the war that followed Plessis-Praslin distinguished himself in various battles and sieges in Italy, including the action called the "Route de Quiers" and the celebrated "Quadrilateral" operations round Turin.
In 1640 he became governor of Turin, and in 1642 lieutenant-general, and after further service in Italy he became a Marshal of France (1645) and second in command in Catalonia. During the first War of the Fronde, which broke out in 1649, he assisted Condé in the brief siege of Paris; and in the second war, remaining loyal to the queen regent Anne of Austria and the court party, he won his greatest triumph in defeating Turenne and the allied Spaniards and rebels at Retbel (or Blanc-Champ) in 1650.
He then held high office at the court of Louis XIV, became minister of state in 1652, and in November 1665 was created duc de Choiseul. He was concerned in some of the negotiations between Louis and Charles II of England which led to the treaty of Dover (1670), and died in Paris on December 23, 1675.