In 2005 Jeroen created a documentary film about the hip hop movement in Brazil together with Dre Urhahn. The film, called Firmeza Total, investigates the role global youth culture plays in the lives of young people in the Favelas of Rio and Sao Paulo.

After seeing what influence culture can have for the self image of resilient communities and their members, Koolhaas and Urhahn founded the urban art project called Favela Painting. Three large scale mural projects ensued in Rio de Janeiro which received worldwide media coverage.

They went on to create projects in Philadelphia, Miami, Haiti, Curaçao and Holland. Favela Painting has extended the idea of mural art to an architectural scale intervention where houses are structurally improved and even surrounding infrastructure is treated. Currently Koolhaas works as an independent artist based in Rotterdam.