Gary Tan was a pioneer in the Direct Honours Programme of the National University of Singapore and received his B.Sc (1st class Honours) from NUS. He received his M.Sc and Ph.D from the University of Manchester , U.K.

He has been lecturing at the School of Computing , National University of Singapore since 1990, and was the recipient of Teaching Awards of the Faculty of Science in both 1992 and 1998, the Teaching Excellence Awards from the School in 1999, 2002, 2016 and the NUS Annual Teaching Excellence Award for 03/04, 04/05 and 06/07. He is also on the ATEA Honour roll for 2008. His research interests include parallel and distributed computing, scheduling and load balancing, declarative multiprocessors, parallel and distributed (interactive) simulation and High Level Architecture. He is currently working on Symbiotic Simulation and Traffic Simulation. He is a member of the Modelling and Simulation Group which is part of the Computer Systems Lab.

He has served as Chair of the NUS PROSE committee, a cross-faculty agency tasked with promoting the use of good English in the University. He was also a Resident Fellow of Kent Ridge Hall (1993-2003), and was Master of Sheares Hall (2003-2013). He is now Vice Dean of Student Life at the school.
He has had project collaborations with KTH (Royal Institute of Technology),Sweden, and FOI (Swedish Defence Research Agency), and is a collaborator with SMART, and Beihang University.

He serves on the program committee of Distributed Simulation and Real-time Systems Symposium, and is on the Editorial Board of the International Journal of Modelling, Simulation, and Scientific Computing (World Scientific). He was Co-chair of AsiaSim2013 ( held in Singapore in November 2013). He was Program Chair of DSRT 2016 held in London, and Conference Co-chair of SIMUTOOLS 2016 held in Prague. He is president of the Society of Simulation and Gaming of Singapore (SSAGsg) and he is currently Chair President of the ASIASIM federation.