De Marquemont was born on 30 September 1572 in Paris, France, where his father worked in the secretariat of the King.

[2] When Duperron left Rome, de Maquemont remained behind, by order of King Henry, as counsellor to the French ambassador to the Holy See.

In 1616, de Marquemont caused some controversy when he decreed that sisters of the Order of the Visitation of Holy Mary would no longer be allowed to live semi-cloistered lives but would instead be forced to "observe strict enclosure" like other female orders.

Also in 1616, priests of Bérulle's Oratory of Jesus moved to the Choir school; and the Carmel of Lyon was founded by Mère Marie de Jésus on the hill of La Croix-Rousse.

De Marquemont was elevated to cardinal on 19 January 1626 and was appointed Cardinal-Priest of the Church of Trinità dei Monti the following month.