Polshek first worked for
I. M. Pei,
Ulrich Franzen, and other architects, before establishing his firm – James Stewart Polshek Architect – in 1963. Some of the first projects he worked on were two research facilities in Japan, as well as collaborating with
Walfredo Toscanini to design a
Midtown Manhattan community center. The majority of his firm's projects were in the United States, with many in
New York City. These included the
Ed Sullivan Theater,
Seamen's Church Institute at the
South Street Seaport,
Sulzberger Hall at
Barnard College, the Skirball Institute of Biomolecular Medicine and Residence Tower at
New York University, and the refurbishment of
Carnegie Hall. Under his leadership, the curriculum was revised and extended to encompass urban planning, real estate, and historic preservation. In 2003, Polshek served as an architectural adviser to the selection committee that chose
SANAA as architects for the
New Museum building. After retiring from his firm's partnership in 2005, Polshek maintained the title of design counsel to Ennead Architects (the new name of that firm). He served as the architect commissioner on the NYC Design Commission during the mid-2010s. His book,
Build, Memory, was published in April 2014 by Monacelli Press. ==Personal life==