Xenos attended New York University and earned a BA in Politics in 1972. He earned an MA in Political Science from the University of Michigan in 1974 and completed the York University Programme in Social and Political Thought in 1976. Continuing his post-graduate education at Princeton University, Xenos would attain an MA in Politics in 1978 and PhD in Politics in their Program in Political Philosophy in 1984.
Early in his career, Xenos was a Lecturer at the Residential College, University of Michigan, Ann Arbor and Fellow Society of Fellows in the Humanities, and Lecturer in the Department of Political Science at Columbia University. He joined the faculty of UMass Amherst in 1984 as an Assistant Professor in the Department of Political Science. He became an Associate Professor in 1990 and a Professor in 1998. Xenos has been a Visiting Professor at the University of California, Berkeley and Amherst College.
Xenos' teaching interests include modern political theory, the politics of European film, and issues in political theory. In 2007, he published Cloaked in Virtue, centered on Leo Strauss and the Rhetoric of American Foreign Policy.