From 1962 to 1967 he taught at the University of Ottawa, and from 1967 to 1996 he taught at the University of Waterloo. He retired in 1996, but continues to remain active in the field.
Brzozowski is particularly known for his work on regular expressions and the algebraic theory of automata.
John Brzozowski has written two books: Digital Networks (Prentice-Hall, 1976, with Michael Yoeli) and Asychronous Circuits (Springer-Verlag, 1995, with C.-J. H. Seger).