He was born in Brussels, the son of Cornelis van Aarsens, also a statesman.

His talents commended him to the notice of Advocate Johan van Oldenbarnevelt, who sent him, at the age of 26 years, as a diplomatic agent of the states-general to the court of France.

[1] His conduct of affairs having displeased the French king, he was recalled from his post by Oldenbarneveldt in 1614, after the French ambassador Benjamin Aubery du Maurier had demanded Aarsens' recall.

[2] Such was the hatred he henceforth conceived against his former benefactor, that he did his very utmost to effect Oldebarneveldt's ruin.

He was sent on special embassies to Venice, Germany and England, and displayed so much diplomatic skill and finesse that Cardinal Richelieu ranked him among the three greatest politicians of his time.