Kees Christiaanse is an architect and urban planner from the Netherlands. He is the founding partner of internationally celebrated KCAP Architects&Planners. With offices in Rotterdam, Shanghai and Zurich, KCAP works on architectural and urban design projects throughout Europe and Asia.

Next to his activities as architect, Kees Christiaanse was the Curator of the 4th International Architecture Biennale Rotterdam in 2009 entitled "Open City: Designing Coexistence" and is since 2010 program leader of the Future Cities Laboratory (FCL) in Singapore. He is a proponent of the idea of "open city" and "mixed communities" as a way of counteracting the ongoing move toward gated communities. Christiaanse believes that architecture and urban design should promote interactions among citizens rather than isolation.
Since 2003, he is the Chair of Architecture and Urbanism at ETH, Zurich, from 1996 – 2003 he has taught at the Technical University of Berlin and had visiting professorships at various universities among which the London School of Economics and the Berlage Institute in Rotterdam. Just recently he was appointed Chairperson of the External Advisory Board of the Architecture and Design Department of the Singapore University of Technology and Design.

Between 1980 and 1989, Christiaanse worked for the Office of Metropolitan Architecture, becoming a partner in 1983. He studied architecture at the Delft University of Technology.