Childhood bullying victimization was linked to several debilitating long-term outcomes, including a doubled risk for suicide attempts in adulthood and an increased risk for anxiety disorders in adolescence. While several studies focused on self-harm or suicidal outcomes associated with bullying in adolescents, few identified the sex-specific neurological, cognitive, and suicidal ideation outcomes associated with bullying victimization in preadolescent children. Additionally, no studies examined whether changes in cortical morphometry might mediate the impact of victimization on cognition. Furthermore, most previous studies that evaluated bullying victimization and neurological or cognitive outcomes were limited by relatively small sample sizes. We used data from the ongoing, longitudinal Adolescent Brain Cognitive Development (ABCD) Study dataset of 11,875 children to determine the cross-sectional (baseline) and longitudinal (matched sample from baseline and second annual follow-up visits) sex-specific neurobiological outcomes associated with bullying victimization. We also performed a methodological study to examine the importance of including socioeconomic factors in all analyses, while replicating the results from a prior study on the impact of initiation of tobacco use on brain morphometry and cognition. This dissertation reports on several novel findings. First, we found that bullying victimization was associated with persistently poorer cognition at baseline and at the second annual follow-up. Second, we identified several novel sex-specific relationships between bullying, self-harm, and behavioral problems in preadolescent children. Third, bullying victimization was associated with larger cortical and subcortical volumes, larger cortical surface area, but thinner cortices. Fourth, larger surface area in the fusiform gyrus partially suppressed (compensated for) and thinner precentral gyrus cortices partially mediated (contributed to) the effect of bullying on cognition. Additionally, our methodological study emphasized the need to adjust for socioeconomic factors when addressing complex human behaviors and brain development. Together, these findings support our overall hypothesis that bullying victimization in preadolescent children is linked to several major neurobehavioral and brain morphometric outcomes. Our findings can better inform schools and communities of the negative consequences of bullying victimization and help them design interventions and treatments that address potential contributory factors based on sex, socioeconomic level, and race/ethnicity.