He then joined the U.S. Navy, where he became gunnery officer on the Essex-class aircraft carrier USS Bon Homme Richard (CV-31).

[3] After graduation Whitin started his academic career as associate professor at Princeton University in its Economics Department.

In 1953 he moved to the Massachusetts Institute of Technology, where he was appointed professor of economics in the School of Industrial Management.

In 1963 he moved back to Connecticut to the Wesleyan University, where he was appointed Chester D. Hubbard Professor of Economics and Social Sciences, where he stayed until his retirement June 30, 1993.

In 1958 Whitin and Harvey M. Wagner wrote the article "Dynamic version of the economic lot size model.