Michael Johnson is a Professor in Engineering at the University of New South Wales and Emeritus Professor of Mathematics and Computer Science at Macquarie University.

His research area is Category Theory, and he was one of the first to develop tools for the mathematics of higher dimensional category theory, and one of the very first to engage in Applied Category Theory, beginning with a number of consultancies in the early 1990s.  He convened the first ever conference in Applied and Computational Category Theory at the Research institute for Symbolic Computation in Linz, Austria, in 1996.  Applied Category Theory is now a world wide initiative, and he is the Program Chair for the Applied Category Theory Conference to be held at the University of Oxford in 2024 (preceded by annual meetings at Leiden, Cambridge, Oxford, MIT, Strathclyde and UMaryland).

He was Foundation Director of the Macquarie-DEC ICT Innovations Centre (2002-2012) and Founding Scientific Director of the Optus Macquarie University Cyber Security Hub, and he is a Director and Company Secretary of Dunmore Lang College. Formerly he was the Head of the Department of Computing (1997-2000), Associate Director of the Centre of Australian Category Theory (1999-2015) and Vice-President and Chair of the University's Academic Senate (2006-2008). He was runner up for the Inaugural (1997) Australian Award for University Teaching in all Science disciplines. He held continuous Australian Research Council large/discovery grant funding for over 20 years and he served the ARC on successive selection panels for The Australian Laureate Fellows (the highest individual award of the ARC), as well as in earlier years the Future Fellowships. 

Nationally he was the Australian Computer Society's Board Director for Professional Standards (2011-2015 and 2017-2023), he has chaired numerous ACS and other accreditation inspections, and he served on CORE's Curriculum Committee as well as the Decadal Plan for Mathematics Curriculum Committee for Universities. Internationally he has served as Chair (2019-2023) and Deputy Chair (2015-2019) of the Seoul Accord, he has been a consultant to two European Commission FP7 projects and he has regular academic activities at several institutions in Europe and North America. In recent years he has acted as an advisor and reviewer for a number of countries, especially in the wider Asia-Pacific region, seeking to establish or improve their accreditation systems for IT and software engineering.

Before his tenured roles he obtained honours degrees in Mathematics and Psychology, a Graduate Diploma of Education, a PhD in Pure Mathematics and a National Research Fellowship, and he engaged in psychological research and statistical consulting as well as industrial software engineering.

Michael is a longstanding Fellow of the Australian Mathematical Society, a Fellow and Certified Professional of the Australian Computer Society, and a life member of the American Mathematical Society and of the ACM. More recently he has been elected as a Fellow of the Governance Institute of Australia and awarded a prestigious Honorary Life Membership of the ACS.