He was named bishop of Amiens in 1552 by Henri II, with the patronage of Cardinal Charles de Lorraine-Guise.

But Bishop Nicolas continued to serve the Monarchy, as an agent of Francis I of France and Mary, Queen of Scots in Scotland from October 1559 to 15 July 1560 during the Scottish Reformation.

Pellevé's intervention was unsuccessful, and in any event a Peace (the Treaty of Edinburgh) was worked out between France and Scotland following the death of the Regent Mary of Guise (10 June 1560), which made a military expedition impossible.

[7] During his absence in Rome from 1574 until 1592, his diocese was administered for him from 1579 by Christophe de Chéfontaine, titular bishop of Caesarea, former Minister General of the Friars Minor.

In 1592 Pellevé was named archbishop of Reims by the Pope, without any notification on the part of the King of France, Henri IV.

[12] In 1593 he obtained the benefice of the Abbey of Toronetum (S. Maria de Floregia) in the Diocese of Frejus.

When Henri de Navarre renounced his heresy and apostasy in July 1593, the Cardinal was in a very difficult position politically and the "Estates" in confusion.