Suicide is among the leading cause of death in children and adolescents. While suicide risk is known to be heritable, statistically well-powered genomics studies of children have been sparse, limiting our understanding of whether, when, and how genetic risk factors of suicide affect children’s suicidal behaviors and risk outcomes. In this study, it was showed that genetic susceptibility to adulthood suicide attempts (SAs), assessed based on the largest GWAS of adult SAs, is associated with suicidal behaviors in 11,878 pre-adolescent US children, after accounting for children’s sociodemographic backgrounds, parental history of suicide, and children’s psychopathology problems. Although the predictive utility of the genetic risk factors is still modest, future efforts may benefit from utilizing genetic data when developing proactive screening and early intervention strategies for mitigating suicide risk in children.