Objective To investigate longitudinal relationships between parenting practices in childhood and adolescent suicidality, and assess the mediating role of emotional and behavioral symptoms. Methods Data were drawn from the National Longitudinal Survey of Children and Youth, a Canadian population-based longitudinal cohort study. The sample included 9,490 children aged 10–11 who were followed up biennially to ages 14–15. Parents reported their positive and punitive parenting practices when children were 10–11. Adolescents self-reported symptoms of depression/anxiety, hyperactivity, conduct disorder, and social aggression at 12–13, and past-year suicidal ideation and suicide attempts at 14–15. Results The inverse associations between positive parenting at 10–11 and suicidal behaviors at 14–15 were significantly mediated by symptoms of hyperactivity, conduct disorder, and social aggression at 12–13. Direct relationships between punitive parenting and suicidal behaviors were observed. These associations were significantly mediated by hyperactivity and, among boys only, by conduct disorder and social aggression. The association between punitive parenting and suicide attempt was additionally mediated by depression/anxiety. Conclusions Parenting in childhood may be associated with adolescent suicidality both directly and indirectly through emotional and behavioral symptoms. Interventions aimed at reducing the use of harsh disciplinary strategies and promoting positive parent–child interactions may reduce the burden of adolescent suicidality.