Adolescence is a time of heightened vulnerability for both peer victimization (PV) and internalizing symptoms. While the positive association between them is well established, there is little understanding of the mechanisms underpinning this relationship. To address this gap, the current study aimed to investigate sleep hygiene and school night sleep duration as individual and sequential mediators of the relationship between PV and both depressive and social anxiety symptoms during pre- to mid-adolescence. The study drew upon a community sample of 528 Australian youth aged 10–12 years at baseline (Mage = 11.19, SD = .55; 51.1% boys) and data were collected over five annual measurement occasions. Direct and indirect longitudinal and bidirectional associations were examined using cross-lagged panel analysis. There was no evidence of sequential mediation through both sleep hygiene and sleep duration to depression and social anxiety. Instead, the findings show that sleep hygiene mediated the prospective association between PV and both depressive and social anxiety symptoms, and between PV and sleep duration. Overall, sleep hygiene represents a modifiable transdiagnostic factor that can be targeted to break the cycle of PV, inadequate sleep, and internalizing symptoms.