Dr Ong is a senior consultant child psychiatrist from the Department of Developmental Psychiatry in Institute of Mental Health (IMH). He obtained his Masters in Medicine (Psychiatry) in 1999 and Graduate Diploma in Psychotherapy in 2001 from the National University of Singapore. Since returning from his research fellowship in New York’s Columbia University in 2005 under the MInstry of Health's (MOH) Health Manpower Development Plan (HMDP), he has been deeply engaged in outpatient services for children and adolescents with psychological problems and has conducted research work in mood disorders, self-harm, cyberbullying and Attention-Deficit Hyperactivity Disorder.

As a head of department for over ten years, Dr Ong was further selected to attend an adminstration HMDP organized by Harved Business School in 2014 and a team HMDP on Trauma System Therapy at NYU Child Study Center USA, in 2018. Among several awards that Dr Ong had received throughout his professional career, notable awards included the National Day Award – Public Administration Medal (Bronze) Medical in 2020 and the National Healthcare Group (NHG) Distinguished Senior Clinician Award (DSCA) in 2024 in recognition of his years of public service and leadership in the field. 

Topics such as anxiety, depression and trauma are close to his heart. He is a frequent speaker in public forums and media interviews on child mental health issues. In addition to teaching three medical schools in Singapore, he is also the Clinical Education Lead of IMH. His authorship spans various relevant topics on children and adolescent mental health in peer-reviewed scientific journals and book chapters.