Dr Khoo Zi Xean graduated from the Yong Loo Lin School of Medicine, National University of Singapore with Bachelor of Medicine and Bachelor of Surgery degree in 2005. He attained postgraduate qualifications with the Royal College of Paediatrics and Child Health (UK) in 2012.

His teaching appointments include:
- Clinical Assistant Professor, Duke-NUS Graduate School of Medicine Singapore
- Adjunct Assistant Professor, Yong Loo Lin School of Medicine, National University of Singapore
- Adjunct Assistant Professor, Lee Kong Chian School of Medicine, Nanyang Technological University
- Core Faculty Member, Singhealth Paediatric Medicine Residency Program
- Advanced Paediatric Life Support Instructor

He was awarded the Singhealth Best House Officer Award in the Department of Orthopedic in 2005. In the same year, he was also awarded the Singhealth Best House Officer Award in the Department of Obstetrics and Gynaecology. Dr Khoo also held the title of Chief Registrar for the Department of Paediatrics for the period from Feb 2014 to July 2014. He received awards for Singhealth Residency in Singhealth Excel Outstanding Resident Award (2014), Dean's Award for Teaching Excellence (2018), Singhealth Quality Service Award(Silver) (2019) and Singhealth Quality Service Award(Hero Award) (2021).

He is passionate about healthcare quality improvement and assurance. He initiated many quality improvement projects and actively participate in various patient safety activities. Dr Khoo is a member of Hospital Patient Safety and Risk Council and have also recently completed Lean-Sigma Black belt course.