Professor Hawkes trained in pediatric endocrinology at Children’s Hospital of Philadelphia, the top ranked Endocrinology Centre in the United States. He was appointed as a Consultant at The Children's Hospital of Philadelphia in 2015. In addition to his work as an endocrinologist, he was the Clinical Director of the number 1 Diabetes Centre in the United States. After 8 years, he returned to Ireland in 2020 when he was appointed as a consultant paediatric endocrinologist at Cork University Hospital.

In addition to his current role, he is currently an advisor to the Endocrinology programme of The Children's Hospital of Philadelphia and an Adjunct Assistant Professor at the University of Pennsylvania. Prof. Hawkes is an internationally leading researcher in paediatric endocrinology and is regularly invited to speak at international conferences. His expertise includes the evaluation of children with short stature, early & late puberty, as well as on thyroid issues, adrenal problems and diabetes. Prof. Hawkes has published over 100 articles and book chapters, including leading the discoverty of new endocrine diseases, investigations and treatments. Dr. Hawkes' clinical expertise has led to invitations to advise on the care of children with complex endocrine disease in other countries, including as a visiting consultant to the United Arab Emirates.

In addition, Prof. Hawkes holds a number of international leadership positions in pediatric endocrinology. He is a member and chair of a number of subcommittees of the Pediatric Endocrine Society of North America, and is also a member of the editorial board for the Journal of Clinical Endocrinology and Metabolism, one of the leading medical journals for the specialty.