After the war, in 1946, he joined the Architectural Review (London) as assistant editor.
[3] Whiffen moved to the United States in 1952, where he held lecturer positions at Massachusetts Institute of Technology and then at the University of Texas.
[4] He moved to Arizona State University in 1960 where he held various positions, and finally as Professor Emeritus.
[3] He corresponded extensively with several other leading architectural historians including Sir Nikolaus Pevsner, Henry-Russell Hitchcock and Sir John Summerson, plus architects including Walter Gropius, Paul Schweikher, and Bart Prince.
[3] Photographs by Marcus Whiffen are held at the Conway Library in the Courtauld, London, and are being digitised.