Simon is a Senior Lecturer in  International Relations at the University of East Anglia, Senior Fellow on Global Cities at the Chicago Council on Global Affairs, and Senior Fellow at University College London's City Leadership Laboratory. He holds a doctorate in International Relations from the London School of Economics, where he was Michael Leifer Scholar in International Relations.

His latest book, Global Cities and Global Order, published by Oxford University Press, was the winner of the 2018 ECPR Hedley Bull Prize for substantial and original contribution to international relations theory. It was also shortlisted for the 2017 British International Studies Association Susan Strange Book Prize.