Under the guidance of his father, his grandfather and his cousin Louis Phélypeaux, marquis de La Vrillière, Jean-Frederic was trained from childhood to be secretary of state to the king of France.

Jean-Frederic had right en survivance to the position of secretary of state, under the Regent, Philippe II, Duke of Orléans, as his father Jerome had purchased the office with the right of inheritance.

Five years later on 16 August he began his duties as ministre de la marine to Louis XV administering the navy, colonies and seaborne trade.

[1] Skilled in military and naval strategy, Maurepas enabled the French Navy to regain previously lost prestige and France was once again recognized as a maritime power.

[1] Over his career as administrator he held the positions of chamberlain of the royal household, minister of the marine, and director of the secret service, fulfilling his duties with efficiency and precision.

At the outset of his new career he showed his weakness by recalling to their functions, in deference to popular clamour, the members of the old Parlement ousted by Maupeou, thus reconstituting the most dangerous enemy of the royal power.