Background: Parenting styles are significantly associated with self-harm (SH) in adolescents. Nevertheless, little is known about the mechanism underlying this association. This study primarily aimed to evaluate the potential mediating role of impulsivity in the association between parenting styles and SH in Chinese adolescents. Methods: Self-administered questionnaires were used to conduct a survey among a sample population consisting of 3146 adolescents in southwest China. Logistic regression analyses were performed to evaluate the association between parenting styles, impulsivity, and SH. A path model investigation further examined the mediating role of impulsivity in terms of the association between parenting styles and SH. Results: The age range of participants was 10 to 17 years old. The prevalence of SH was 47.0% (95% CI: 36.3–58.0%). Impulsivity, less paternal emotional warmth, maternal over-protection, and rejection were significantly associated with SH. The path model identified impulsivity as a salient mediator, accounting for 23.4% of the total association between parenting styles and SH. The hypothesized path model indicated differences in the parenting styles of fathers and mothers: Impulsivity played a significant mediating role, though only in respect to the maternal over-protection and rejection paths. Conclusions: For Chinese children and adolescents who experience a harsher maternal parenting style, impulsivity-centered intervention measures might be effective in reducing SH related to parenting styles. © 2021, The Author(s).