Non-suicidal self-injury (NSSI) is increasingly prevalent among patients with bipolar disorder (BD), raising concerns in psychology and mental health. Investigating the incidence and factors associated with NSSI is crucial for developing prevention and intervention strategies.NSSI behaviors were identified using the Ottawa Self-injury Inventory. The Clinically Useful Depression Outcome Scale supplemented with questions for the DSM-5 specifier of mixed features (CUDOS-M) and the Mini International Neuropsychiatric Interview (Hypo-)Manic Episode with Mixed Features-DSM-5 Module (MINI-M) were used to evaluate clinical symptoms. Non-parametric tests, chi-square tests, point-biserial correlation and logistic regression analyses were employed for the purposes of data analysis.The enrolled sample comprised 1044 patients with BD from 20 research centers across China. Out of 1044 individuals, 446 exhibited NSSI behaviors, with 101 of them being adolescents, leading to a prevalence of 78.3 % among adolescent patients. The most common methods for females and males were "cutting" (41.2 %) and "hitting" (34.7 %), respectively. By binary logistic regression analysis, young age, female, bipolar type II disorder, with suicidal ideation and mixed states, depressive symptoms and without family history of mental disorder were correlates of NSSI in patients with BD (P < 0.05).As a cross-sectional study, causality between NSSI behaviors and associated factors cannot be established. Reporting and recall biases may occur due to self-rating scales and retrospective reports.Our study indicates a concerning prevalence of NSSI, particularly among young patients with BD in China. Future research should focus on understanding NSSI behaviors in this population and developing effective interventions.Copyright © 2024. Published by Elsevier B.V.