Wee Loon Ong graduated from Monash University with BMedSci and MBBS. Following completion of internship at the Alfred Health, he pursued an MPhil in Epidemiology at the University of Cambridge, graduating first in the cohort with the GSK Prize. He subsequently undertook Radiation Oncology specialist training through the Royal Australian and New Zealand College of Radiologists (RANZCR) Clinician-Scientist Training Pathway within the Victorian/ Tasmanian Network, rotating through the Peter MacCallum Cancer Centre, Ballarat Regional Integrated Cancer Centre, and Austin Health Olivia Newton-John Cancer Centre, while concurrently pursuing a Doctorate of Medicine (MD) higher research degree through the University of Cambridge. He is currently a Radiation Oncology Prostate Cancer Fellow at the Alfred Health Radiation Oncology. He is also an Adjunct Lecturer at the Department of Epidemiology and Preventive Medicine, Monash University, and Adjunct Research Fellow at the University of Melbourne. 

He is actively involved in the RANZCR College activities, including: being the past Chair of the Radiation Oncology Trainee Committee (ROTC), a member of the Faculty of Radiation Oncology (FRO) Council, the FRO Quality Improvement Committee (QIC), the Annual Scientific Meeting (ASM) Management Committee, as well as the Network Governance Committee for the Victoria/ Tasmania Radiation Oncology Training Network (VICTRANET). He is involved in the Trans-Tasman Radiation Oncology Group (TROG) as a member of the Genitourinary Working Party. He is also a member of the European Society of Radiotherapy and Oncology (ESTRO), Australian and New Zealand Urogenital and Prostate Trial Group (ANZUP), Cooperative Trials Group for Neuro-Oncology (COGNO), and Australasian Gastro-Intestinal Trial Group (AGITG).

His clinical interests are primarily in genitourinary (GU) cancers (including brachytherapy), and central nervous system (CNS) cancers. His research interests are in health services, including research on contemporary pattern of cancer care, and adoption of evidence-based practice in radiation oncology using population-based administrative healthcare databases and registry database such as the Prostate Cancer Outcomes Registry (PCOR). He was involved in the development of value-based patient-centred standard set of breast cancer outcomes as part of the ICHOM Breast Cancer Working Group. He has published widely, relative to opportunity, with more than 30 publications to date, including first author publications in JAMA Oncology, and Medical Journal of Australia. He is peer-reviewer for several journals including the British Journal of Cancer, Radiotherapy and Oncology, and BJUI.