Professor Frizelle earned his medical degree from the University of Otago in 1985 and completed general surgical training in New Zealand, achieving FRACS status in 1992. He pursued advanced colorectal and laparoscopic training at the Mayo Clinic and Scottish institutions before returning to New Zealand in 1996 as a Senior Lecturer, later becoming Professor of Colorectal Surgery in 2000.

He led the Academic Department of Surgery from 2006-2019 and served as Clinical Director of General Surgery for Christchurch and the West Coast (2022-2024). His expertise spans colorectal cancer, inflammatory bowel disease, and complex pelvic surgery. Professional honors include appointment as an Officer of the New Zealand Order of Merit and awards from the Royal Australasian College of Surgeons.

He has chaired multiple professional committees and organizations focused on surgical education and colorectal cancer policy. With over 500 peer-reviewed publications and 350+ invited presentations, he remains active in research and quality improvement initiatives. He currently serves as President of the Colorectal Surgical Society of Australia and New Zealand.