As an architectural historian, Mart Kalm has mainly studied the work of Estonian architects in the 20th century (before and after World War II). Kalm has been active as an architecture critic and is interested in landscape and interior architecture. Kalm has been a long-time member of the Expert Council for Architectural Monuments of the National Heritage Board as well as the Head of the National Heritage Council 2006–2010. From 2010 to 2013 he was the Co-Chair of the Estonian delegation to the UNESCO World Heritage Committee.
Since 1992 Mart Kalm has been working at the Estonian Academy of Arts. In 2000 he became a professor at the academy, and between 1994 and 2007 he built the Institute of Art History. From 2007 to 2012 he was the Dean of the Faculty of Art and Culture. In January 2015 he became Rector of the Estonian Academy of Arts.
In 2010 Mart Kalm became the first art historian to be elected a member of the Estonian Academy of Sciences. Since 2014 he has held the position of Vice-President of the Estonian Academy of Sciences.