Being non-heterosexual, particularly bisexual, is associated with high rates of engagement in NSSI amongst young adults. The goal of the present study was to determine if parenting practices, specifically parental monitoring, and sexual orientation moderate engagement with NSSI. Undergraduates (N = 1,353) completed a survey on sexual orientation, non-suicidal self-injury (NSSI) acts, and multiple aspects of perceived parental monitoring during high school. Moderation analyses revealed that most facets of parental monitoring were similarly negatively correlated with NSSI for both individuals whose sexual orientation where nearly, or entirely, gay and heterosexual youth. Youth who were neither exclusively heterosexual nor exclusively gay (mixed sexual orientation) reported the most NSSI acts, and no facet of parental monitoring predicted reduced NSSI acts for this group. While previous literature shows that many aspects of parental monitoring may be protective against engagement in health risk behaviors, the present study adds to these findings that similar aspects are negatively associated with self-injurious behavior for some, but not all, individuals. More research is needed to better understand the causes of increased NSSI for individuals with a mixed sexual orientation.