Youth with autism spectrum conditions have been shown to be at an increased risk for bullying victimization. The overall aim of this study was to identify factors associated with increased risk for bullying victimization in youth with autism during middle childhood to early adolescence (aged 5–12 years) and to explore the potential time-ordered associations between bullying victimization and mental health problems 12 months later. The average age of the youth with autism was 7.90 years ( SD = 2.33), 86% were male, 34.6% had an intellectual disability, and 84% were White, non-Hispanic. Youth with autism who experienced bullying victimization (vs no victimization) were older in age, had more severe autism symptoms, and higher levels of internalizing and externalizing mental health problems at study onset. Using two cross-lagged structural equation models, the associations between maternal report of youth bullying victimization and teacher report of youth mental health problems using two waves of data were tested. Internalizing and externalizing mental health problems at Time 1 did not relate to change in likelihood of being bullied 1 year later. In contrast, bullying victimization at Time 1 was associated with an increase in internalizing mental health problems ( β = 0.24, p < 0.05). Lay Abstract Youth with autism spectrum disorders are disproportionately at risk for bullying victimization compared to typically developing children and adolescents. While internalizing and externalizing mental health problems have been linked to victimization experiences, few studies have examined the longitudinal effects bullying victimization experiences may have on youth mental health outcomes. The present study investigated longitudinal associations between bullying victimization and mental health problems in a sample of children with autism in middle childhood to early adolescence (aged 5 to 12 years). Findings from our study suggest that youth with autism who experienced bullying victimization (versus no victimization) were older in age, had more severe autism symptoms, and higher levels of internalizing and externalizing mental health problems at study onset. Though externalizing mental health problems at study onset (Time 1) did not relate to change in the likelihood of being bullied one year later (Time 2), experiences of bullying victimization did relate to an increase in parent reports of internalizing mental health problems. This study expanded on previous cross-sectional studies by including two waves of data in a relatively large sample of youth with autism and highlights important information that may be helpful in adapting approaches to intervention at the individual level. Moreover, our findings support the need for bullying programs that may need to focus particular attention to subgroups of youth with autism who may be most at-risk for bullying victimization such as those with more autism symptoms and those with past experiences of victimization (given the chronic nature of bullying).