<p>Experts call for the application of positive psychological interventions (PPIs) to bolster treatment for people with substance use disorders. However, there remains a gap in developing PPIs that promote positive dispositions important to people with substance problems from collectivist societies. In this study, we developed a PPI that can promote well-being and recovery by boosting the locus-of-hope of people with substance use disorders in a therapeutic community. Using a double-blind, randomized controlled trial with pre-treatment, post-treatment, and 1-month follow-up design, we tested the efficacy and mechanisms of the Locus-of-Hope Enhancement Program (LEAP) for Well-being and Recovery, a PPI that fosters cognitive hope. One hundred thirty-eight participants were randomly assigned to LEAP (<i>n</i> = 73) or a stress management control (<i>n</i> = 65). Outcomes were measured using the Locus-of-Hope Scale, Flourishing Scale, Brief Assessment of Recovery Capital, Dimensions of Change Instrument, and the Group Working Alliance Inventory. Results show that participants who received LEAP reported better internal locus-of-hope, external-peer locus-of-hope, community process experience, and group working alliance than the control group across time, but not on external-family locus-of-hope, external-spiritual locus-of-hope, psychological well-being, and recovery capital. LEAP indirectly boosted psychological well-being and recovery capital through community process experience and group working alliance post-treatment. LEAP’s indirect effect was sustained for recovery capital but not for psychological well-being at the 1-month follow-up. The current study provides initial evidence of the efficacy and mechanisms of a PPI for people with substance use disorders that promotes hope, leading to better well-being and recovery.</p>