Background: Given their modifiable nature, understanding the intrapersonal factors involved in the cessation of non-suicidal self-injury (NSSI) is needed to inform existing therapeutic approaches and explore novel avenues for supporting individuals with NSSI. This study aimed to examine the relative contributions of and interactions among intrapersonal factors (self-concept, emotion regulation, and cognitive flexibility) in distinguishing between ceased and current NSSI. Methods: 202 adults aged 18-71 years ( M = 31.50, SD = 11.23; 74.75% female) were surveyed to compare facets of self-concept, emotion regulation, and cognitive flexibility that contributed most to discriminating those who had ceased NSSI for one year from those who continued. These intrapersonal factors were also explored as potential indirect pathways between identity and NSSI status. Results: Significant differences between ceased and current NSSI groups were observed across all intrapersonal factors, with moderate to large effects. Most differences persisted after accounting for psychological distress. Less identity fragmentation, greater emotional clarity, internal locus of control, self-liking, access to emotion regulation strategies, and impulse control contributed most to discriminating NSSI cessation after accounting for psychological distress. The relationship between lack of identity and NSSI status operated indirectly through lack of emotional clarity and self-liking. Conclusions: Having a coherent sense of identity, emotional clarity, internal locus of control, self-liking, access to emotion regulation strategies, and managing impulsivity relate to NSSI cessation. These modifiable factors denote several promising intervention opportunities and should be considered in the design of NSSI-specific treatments.