He was the father of Nicolaes Witsen and the son of Jan Witsz(en) and Grietje Claes.

He was baptised on 8 September 1605 in Amsterdam, and began his career as captain of the Schutterij and ended it as hoofdschout (head bailiff).

As a member of the Admiralty of Amsterdam, in 1656, he was sent with a diplomatic mission to England for talks with Cromwell at the laws on shipping.

Witsen was a great patron of painting and supported the painter Rembrandt through his 1653 financial problems by providing him with a loan to buy a house.

[1] Witsen kept a library and was best known for his central role in Bartholomeus van der Helst's painting Peace of Münster which also features a poem by his favorite poet Jan Vos.