Koen van Velsen architects consists of a multidisciplinary team of designers working together on a wide-range of projects ranging from architecture, interior, landscape and urban design.

Projects by Koen van Velsen architects are being recognized and respected, both nationally and internationally. For example, Multifunctional Rehabilitation Centre Groot Klimmendaal was awarded Building of the Year by the Association of Dutch Architects. The building also won the first Hedy d’Ancona Award for excellent healthcare architecture and the Dutch Design public award. In 2011, the building was awarded international health building of the year during the World Architecture Festival. Koen van Velsen architects was nominated in 2013, 2011, 2003, 1992 en 1990 with several buildings for the international European Union Prize for Contemporary Architecture - Mies van der Rohe Award. In 2011, Groot Klimmendaal was a finalist for this Award.
Koen van Velsen received a number of distinctions for his work such as the Mart Stam Award from the city of Amsterdam, the Rietveld Award from the city of Utrecht and the BNA cube, the oeuvre award from the Association of Dutch Architects for his outstanding contribution to Dutch architecture. Koen van Velsen was a member of several architecture juries including the jury of the Abe Bonnema Award, the Hedy d’Ancona Award and the BNA cube.

Between 2009 and 2015, Koen van Velsen was Dutch Railroad Architect on behalf of NS and ProRail. With special attention for an integral approach to design projects, Koen van Velsen strived amongst others for the NSP projects, a better cohesion between train stations and the surrounding public realm and an improved meaning of stations within the public context. From January until September 2015, Koen van Velsen was acting Government Architect and part of the Committee of Government Advisors.