He succeeded his father in that office in 1616, and in the following year attended the assembly of notables at Rouen convoked by the young Louis XIII. In 1618 he was named councillor of state and in March 1624 was called to Paris, where he found favor with Richelieu. He displayed administrative ability and great loyalty to the central government as intendant in Guienne in 1627, where his executive qualities came to the fore, and where it became clear that he had broken with his background in the parlements to become a trusted follower of Richelieu. In 1628 he negotiated the boundary delimitation with Spain. In 1629 he was with the army of the king and cardinal in the War of the Mantuan Succession, where he remained behind at Turin to work on the peace negotiations, after the royal party had returned to France; thus by 1631 he came to know Mazarin, whom he was able to introduce to Richelieu. Servien was one of the signatories of the Treaty of Cherasco and of the treaties with the Duke of Savoy (1631–1632).
He was appointed president of the parlement of Bordeaux in June 1630 but renounced the place when he was offered the post of secretary of state for war by Louis XIII. In 1634 he was the first elected member of the Académie française. Two years later he retired from public life in disgrace as the result of court intrigue.
Servien lived at Angers or on his estates at Sablé until the death of Louis XIII in 1643, whereupon he was recalled to Court by Mazarin, who entrusted him with the conduct, conjointly with the count Claude d'Avaux, of French diplomatic affairs in Germany. After five years' negotiations, and a bitter quarrel with the comte d'Avaux, which ended in the latter's recall, Servien signed the two treaties of October 24, 1648 which were part of the general Peace of Westphalia.
He received the title of minister of state on his return to France in April 1649, and remained loyal to Mazarin during the Fronde. With the cardinal exiled, Servien was minister of state, de facto governor of France with his nephew Hugues de Lionne and his rival Michel le Tellier. He was made Superintendent of Finances in 1653, conjointly with Nicolas Fouquet. He was an adviser to Mazarin in the negotiations which terminated in the Treaty of the Pyrenees (1659). He amassed a considerable fortune, and was unpopular, even in court circles. He died at the Château de Meudon, which he had purchased in 1654 and where he had launched ambitious works of rebuilding.
Servien left an important and voluminous correspondence.