The son of a Schiedam distiller, Johan Windhorst, at the age of 33, left the manufacturing profession to take up painting. In 1922 he stayed briefly in Katwijk aan Zee to take lessons, and whilst there also painted the local scenery. Landscapes and architecture dominate his oil paintings, watercolours and pastels. He also painted during his travels through southern Europe and North Africa. Windhorst also gave lessons to Queen Wilhelmina.