Michael Aizenman (Hebrew: מיכאל אייזנמן; born 28 August 1945) is an American-Israeli mathematician and a physicist at Princeton University, working in the fields of mathematical physics, statistical mechanics, functional analysis and probability theory.

The highlights of his work include: the triviality of a class of scalar quantum field theories in more than three dimensions; a description of the phase transition in the Ising model in three and more dimensions; the sharpness of the phase transition in percolation theory; a method for the study of spectral and dynamical localization for random Schrödinger operators; and insights concerning conformal invariance in two-dimensional percolation.

He was awarded his PhD in 1975 at Yeshiva University (Belfer Graduate School of Science), New York City, with advisor Joel Lebowitz.

In 1987 he moved to the Courant Institute and in 1990 returned to Princeton as professor of mathematics and physics.

Aizenman received honorary degrees (DHC) from Université de Cergy-Pontoise (2009) and Technion (2018), and is a member of National Academy of Sciences (1997), American Academy of Arts and Sciences (2017), and Academia Europaea (2016).