This study aimed to assess the effectiveness of Mindfulness-Based Stress Reduction (MBSR) on internalized stigma and relapse prevention in individuals with substance use disorders. The investigation addresses a clinically relevant area, given the debilitating role of self-stigma in recovery. A sample (n=100) of individuals aged 19-45 was recruited via purposive sampling from a different rehabilitation centre in Peshawar. The study employed a pre-test/post-test design without a control group, utilizing the Substance Use Stigma Mechanism Scale and a Time to Relapse Questionnaire. Data were analysed using paired sample t-tests. The analysis indicated statistically significant reductions (p < .001) in mean scores for both internalized stigma and relapse risk from pre-test to post-test following the MBSR intervention. While the results suggest a positive association between MBSR and the measured outcomes, the methodological design critically limits the validity and generalizability of the findings. The absence of a control group makes it impossible to attribute the improvements causally to MBSR, as confounding variables such as the general therapeutic environment or the passage of time cannot be ruled out. Furthermore, the use of purposive sampling from a single site and the reliance on self-report measures for relapse pose significant threats to external validity and measurement robustness. Therefore, the conclusion that MBSR is "effective" is an overstatement of the evidence provided. This study serves as a preliminary indication for a potentially beneficial intervention, but its recommendation for the widespread integration of MBSR into rehabilitation centres are premature without more rigorous, controlled, and longitudinal research.