Pieter Molijns father was texile-trader from Ghent who left Flanders with his family because of his belief. His son Pieter was baptised in London and around 1609 the family moved to Haarlem.
It was there Pieter was educated as a painter (probably by Esaias van de Velde) and became member of the guild of Saint Luke in 1616.
Molijn became a famous painter and draughtsman soon, he was very active in the guild and educated famous pupils as Gerard Ter Borgh and Allaert Van Everdingen.
From the 17th century on, his work and reputation are compared to Jan Van Goyen, who is stylisticly closely related.