Educated in Dublin, Ireland, Dr. John G. Kennedy earned his doctor of medicine from the Royal College of Surgeons before completing a master of medical science program at University College Dublin. Over the course of his career as a medical practitioner and clinical educator, Dr. John G. Kennedy has returned to University College Dublin and the Royal College of Surgeons on multiple occasions, securing postgraduate degrees in general surgery, orthopedic surgery, and sports medicine.

Dr. John Kennedy moved to the United States in the early 1900s, obtaining a Massachusetts training license in 1994 and a New York medical license in 2003. Since 2019, he has served as an attending physician and chief of the division of foot and ankle surgery at NYU Langone Health in Manhattan. Dr. Kennedy also teaches as a tenure-eligible professor at NYU Langone Health, and writes widely on subjects such as nano arthroscopy and other state-of-the-art, minimally invasive procedures.