Dr Cullen is a medical graduate from the University of Sydney, a qualified specialist physician and intensive care specialist. He works at the Lakeview Private Hospital as a general physician.  He also works at Westmead Private Hospital as a general physician and has a staff specialist appointment at Westmead Hospital as an intensive care specialist.

Dr Cullen’s interests include infectious diseases, perioperative medicine and cardiology. He also has a commitment to community health, running a rural general medicine clinic in outback New South Wales.