<p dir="ltr"><b>Background:</b> Relapse rates following residential substance use disorder (SUD) treatment remain high, with the transition from structured residential care to community living representing a period of extreme vulnerability. Existing relapse prevention models and interventions inadequately address the unique ecological discontinuities and empirically-validated risk and protective factors specific to this critical transitional phase.</p><p dir="ltr"><b>Objectives:</b> This multi-phase sequential study aimed to develop and preliminarily evaluate a relapse prevention model and intervention, specifically designed for individuals preparing for discharge from residential SUD treatment.</p><p dir="ltr"><b>Methods:</b> The research employed a five-phase design: (1) systematic meta-analysis quantifying risk and protective factors for post-residential relapse; (2) scoping review mapping current relapse prevention interventions in residential settings; (3) theoretical development of a relapse prevention model synthesizing empirical findings; (4) operationalization into a manualized 8-session intervention protocol; and (5) single-group pilot study evaluating feasibility, acceptability, and preliminary effectiveness in a Hong Kong residential treatment center.</p><p dir="ltr"><b>Results:</b> The meta-analysis identified potent risk factors including heavy pre-treatment substance use (OR=11.27), treatment non-completion (OR=3.86), and substance-using social networks (OR=3.15), alongside protective factors including positive therapeutic alliance (OR=3.33), employment (OR=2.96), and aftercare engagement (OR=1.73). The scoping review revealed critical gaps in transition-focused interventions. The Transitional Relapse Intervention and Prevention (TRIP) model integrates four evidence-based components: Connection and Commitment, Core Skills for Relapse Prevention, Pro-Recovery Social and Environment, and Structured Transition Planning and Management. The pilot study demonstrated high feasibility and acceptability, with significant pre-post improvements in psychological distress, self-efficacy, and adaptive coping strategies. At six-month follow-up, 56.7% of participants maintained abstinence, with those remaining abstinent showing significantly greater increases in self-efficacy and reductions in substance-use coping during the intervention.</p><p dir="ltr"><b>Conclusions:</b> The TRIP framework addresses critical theoretical and practical gaps in relapse prevention for the post-residential transition period. Preliminary findings support its feasibility, acceptability, and potential effectiveness, warranting larger-scale randomized controlled evaluation. This research contributes a novel, empirically-grounded model that systematically targets high-impact factors specific to this vulnerable population and transition period.</p>