Objective This study aimed to estimate the 5-year mortality among people admitted into a transdisciplinary unit providing combined psychiatric and somatic rehabilitation treatment. Methods In this retrospective study, we analyzed the clinical records of all individuals admitted into the transdisciplinary unit from 01/01/2011 to 12/31/2017 after a suicide attempt using violent means. Vital status was ascertained for these 215 people, a standardized mortality ratio (SMR) was calculated and Log-rank tests were used to identify factors associated with mortality. Results The crude mortality rate was 5.12% (11 deaths) and the SMR was 15.45 (95% CI = [7.71–27.65]; p < 0.001) 5.40 years after admission into the transdisciplinary unit. Factors associated with mortality were: older age (29.91 years versus 25.30 years, p < 0.001), a longer stay in acute care (p = 0.002) and a shorter stay in the transdisciplinary unit (p < 0.001). Conclusion Long-term mortality among people who have attempted suicide using violent means is 15 times higher than in the corresponding general young adult population. This study supports the hypothesis that the severity of a suicide attempt is associated with subsequent excess mortality. Therefore, there is a need to consolidate outpatient facilities that provide appropriate support for this specific population after discharge. These programmes need to ensure the continuity of coordinated psychiatric and somatic care and psychosocial rehabilitation in order to prevent the risk of suicide.