Professor G.J. Melendez-Torres arrived at the University of Exeter in March 2019 to take up a personal chair in clinical and social epidemiology. His work spans health technology assessment (HTA), public health of child and adolescent social development (particularly as it relates to schools), and intimate partner violence. He also leads the School for Public Health Environments Research at Exeter (SPHERE), which is the University's membership in the NIHR School for Public Health Research; the Exeter-Cardiff-Birmingham NIHR Public Health Review Team; and co-lead with Prof Jo Thompson Coon the newly established evidence synthesis group Isca Evidence.

At national level, Professor G.J. Melendez-Torres is the Associate Director for Involvement and Engagement for the NIHR School for Public Health Research. In addition, he is Deputy Director of the Exeter NIHR Policy Research Programme Evidence Reviews Facility. Until July 2023, he led the Peninsula Technology Assessment Group (PenTAG), one of 11 major research units in the UK providing expert advice on the clinical and cost effectiveness of new drugs to the National Institute for Health and Care Excellence. He continues as chief investigator of the platform grant that underpins PenTAG's work, alongside contributing to parallel programmes in health policy and medical technologies evaluation.

Professor G.J. Melendez-Torres holds the citiesRISE Research Chair in Public Mental Health, through which he leads a programme of research to develop new ways of promoting mental health for children and young people around the world.