Janez Kozelj is a full-time professor at the Faculty of Architecture, at the University of Ljubljana, where he lectures on urban design and architectural design. From the fall of 2006 on he has served as Vice-Mayor of the City of Ljubljana.

Between 1974 and 1994 Kozelj was editor in chief of the international magazine for the architectural theory AB (Architectural Bulletin). In his research work he examines operative methods in planning and management of the contemporary city. Professionally, he develops architecture adapted to the environment. His views and discussions have been published in numerous books and presented at international conferences. He has won numerous first prizes for his work on architectural competitions. He has also received two expert awards for his artistic achievements. He has participated in numerous exhibitions of Slovenian contemporary architecture in Europe and the USA. Between the 1980 and 1985 he participated in Skupina Kras (Group Kras) and Studio Znak.