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 Cardinal 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).