Relapse remains a critical challenge in substance use disorder treatment, undermining recovery and perpetuating cycles of dependence. This study examined the influence of family functioning, and resilience on relapse tendency among patients with substance use disorder (SUD) in selected rehabilitation centers in Abuja, Nigeria. A cross-sectional survey design was adopted with the aged mean of 27.43 years and data were collected from 136 SUD patients across eight rehabilitation centers using the Family APGAR Scale, the Brief Resilience Scale (BRS), and the Advance Warning of Relapse (AWARE) Scale. Purposive sampling was employed, with inclusion restricted to medically stable individuals who had completed detoxification and provided informed consent. Data were analysed using descriptive statistics, Pearson correlation, simple linear regression, and multiple linear regression. Results showed that resilience achieved significance within the combined predictive Resilience: β = -.079, p = .358, R² = .236 Family functioning did not independently predict relapse tendency but demonstrated significant positive associations with resilience Family Functioning: β = .047, p = .590, R², suggesting an indirect rather than direct role in shaping relapse outcomes. These findings underscore that effective relapse prevention must extend beyond clinical intervention to encompass the broader psychosocial and environmental context of recovery. It was recommended that rehabilitation centers in Nigeria formally incorporate structured enhancement programs, family psycho-education, and resilience-building curricula into standard treatment protocols, alongside post-discharge aftercare frameworks that address the structural and relational vulnerabilities of patients with substance use disorder.