Ioannis Kontoyiannis (born January 1972) is a Greek mathematician and information theorist.

He is also a Fellow of Darwin College, Cambridge, and Chairman of the Rollo Davidson Trust.

[1] He is an affiliated member of the Division of Information Engineering, Cambridge,[2] a Research Fellow of the Foundation for Research and Technology - Hellas,[3] and a Senior Member of Robinson College, Cambridge.

His research interests are in information theory, probability and statistics, including their applications in data compression, bioinformatics, neuroscience, machine learning, and the connections between core information-theoretic ideas and results in probability theory and additive combinatorics.

In January 2018 he joined the Information Engineering Division at Cambridge University, as Professor of Information and Communications, and Head of the Signal Processing and Communications Laboratory.