Prof Lee is currently the Deputy Group CEO (Regional Health System), SingHealth where he leads population health efforts to enable residents in Eastern Singapore to keep well, get well and live well. His past appointments include CEO of Changi General Hospital, a 1000 bed public general hospital, and Deputy, Director of Medical Services for Health Services and Healthcare Performance in the Ministry of Health Singapore where he led the strategic development and improvement of healthcare services.

Prof Lee is an Adjunct Professor with three institutions of higher learning ie Saw Swee Hock School of Public Health, National University of Singapore, Duke-NUS Medical School and Singapore University of Technology and Design.   He was a member of several international committees under the World Health Organisation, International Hospital Federation and Joint Commission International.

Prof Lee co-edited Singapore's Health Care System: What 50 Years Have Achieved (2015) and contributed the chapter on Strategies for Health Services in the 6th edition of the Oxford Textbook of Public Health (2015). He has also published and presented in international journals and conferences respectively.