Introduction Understanding suicide in more isolated territories is a challenge because of the entanglement of cultural identity with historical, geographical and sociocultural specificities. This knowledge is a necessary precondition for the implementation of targeted prevention strategies in regions such as the French overseas territories (FOT), where data concerning suicidal risk factors is still incomplete. We aim to untangle sociocultural and clinical suicide risk factors by integrating a novel anthropological and psycholinguistic approach into the psychological autopsy method. This article describes the protocol of the clinical study ‘Contribution of Psychological Autopsy to the Understanding of Suicidal Behaviours in Overseas France’ (AUTOPSOM study), designed to identify common or new specific suicide risk factors in four FOT. Methods and analysis A multicentre epidemiological study will be carried out in four FOTs (French Polynesia, Martinique, La Reunion and French Guiana) and at a comparison site in mainland France (La Somme). The methodology will be based on a mixed-methods (quantitative and qualitative) approach using a psychological autopsy to collect clinical data and life events in the deceased’s life. We implemented an exploratory multimethod strategy that combines a succession of epidemiological, anthropological, psycholinguistic and psychological methods with a semiautomated analysis of the discourse of relatives bereaved by suicide. Ethics and dissemination The study protocol (first version) was approved by the French Ethics Committee (CPP OUEST II, approval #22.04267.000122) and the Ethics Committee of French Polynesia (JOPF of 5 April 2022; CEPF opinion n°91 of 29 March 2022). The overall results and the perspectives established at the end of the study will be communicated to the bereaved relatives according to their will and serve for local suicide prevention purposes. Trial registration number NCT05773898.