Kah Weng completed his undergraduate medical training at National University of Singapore, with an intercalated doctorate from University of Oxford. For his PhD study, he worked under Sir Peter Ratcliffe, studying pathways regulated by the von-Hippel Lindau tumour suppressor protein and hypoxia inducible factor.

He subsequently went on to pursue his specialist training in histopathology at Singapore General Hospital and obtained his fellowships from the Royal College of Pathologists (UK) and Royal College of Pathologists of Australasia. His subspecialties of interest are lung and breast pathology.