This study investigates the effectiveness of an evidence-based vocational learning model for vulnerable adults with developmental impairments residing in secure units. Its purpose was to conceptualize and test scalable, structured pedagogical strategies combining the development of vocational skills, behavior rehabilitation, therapeutic engagement, and transition planning. The quasi-experimental longitudinal design that was used was mixed-methods. The finally selected participants (N = 124) were split into the intervention group (n = 62), who were administered the integrated vocational program, and the control group (n = 62), who received normal care. At the baseline, post-intervention (12 months), and six-month follow-up, vocational competency, employability readiness, adaptive functioning, behavioral incidents, and qualitative perceptions were assessed in interviews and observations. Findings showed significant gains in the intervention group. Vocational competency increased from 41.6 (SD = 9.4) to 68.3 (SD = 10.1) post-intervention and remained at 65.7 (SD = 9.8) at follow-up, compared to 42.1 (SD = 8.9) to 49.5 (SD = 9.7) in controls. Employability readiness rose from 18.4 (SD = 4.3) to 34.6 (SD = 5.1), with 38% entering supported employment versus 16% of controls. Adaptive functioning was enhanced (Cohen’s d = 0.89), and behavioral incidences were reduced by 42% compared to 15% in the control group. Qualitative results indicated that there were more self-efficacy, motivation, engagement, and perception of safety. Finally, incorporating organized vocational training in safe rehabilitation improves technical abilities, adaptive behavior, and after-discharge employability. The model shows a high level of sustainability, interdisciplinary cooperation advantages, and reproducibility in safe caring conditions.