BACKGROUND: Non suicidal self injury (NSSI) is a public health concern, and its prevalence has increased significantly following the COVID-19 pandemic. Despite its rising incidence, the neurobiological mechanisms underlying NSSI behaviour in adolescents remain poorly understood. METHODS: A sample of 89 adolescents (46 NSSI positive, 43 NSSI negative) aged 15.39 ± 1.77 years was recruited from clinical settings. NSSI behaviour and psychological resilience were evaluated. Resting-state functional magnetic resonance imaging (Rs-fMRI) was conducted to examine brain connectivity patterns. Data analysis incorporated descriptive and inferential statistics, as well as support vector machine algorithms, to identify the neural correlates of NSSI and resilience. RESULTS: The NSSI positive group had significantly lower resilience scores ( = 23.41,  = 7.95). Connectivity between the sensorimotor and limbic networks was negatively associated with NSSI ( = -0.222,  < 0.05), while connectivity between the sensorimotor and subcortical networks showed a positive association ( = 0.201,  < 0.05). Stronger connectivity between dorsal attention and default mode networks indirectly reduced NSSI by enhancing psychological resilience, highlighting resilience as a critical protective factor. CONCLUSION: These findings underscore the importance of targeting specific brain connectivity patterns and enhancing psychological resilience as crucial components of neurobiologically informed interventions.