Brought to Denmark by his family as a child, Moltke was a page to the future king Christian VI in 1722. In 1730 he became chamberlain to the future king Frederick V. Frederick secured for Moltke the post of court marshal in 1743, and Moltke remained in that post after Frederick V was crowned in 1746. In 1747 Frederick made Moltke a privy councillor, giving him the estate of Bregentved. In 1750 Moltke was made a count.

Moltke was the most influential of Frederick V's advisers. He strongly opposed the liberation of the peasantry. Frederick V died in his arms in 1766, and Moltke was then dismissed from his major posts by the new king, Christian VII. Moltke was recalled the following year to deal with agrarian reforms but was dismissed again in 1770, retiring then to his estate.