OBJECTIVE: This study investigates the association between parental precarious employment (PE) and the mental health of their adolescent children, with a particular focus on how the association differs based on whether the mother or father is in PE. METHODS: This register-based study used the Swedish Work, Illness, and Labor-market Participation (SWIP) cohort. A sample of 117 437 children aged 16 years at baseline (2005) were followed up until 2009 (the year they turned 20). A multidimensional construct of PE (SWE-ROPE 2.0) was used to classify parental employment as either precarious, substandard or standard. The outcome, adolescents’ mental disorders, was measured as a diagnosis of a mental disorder using ICD-10 codes or by prescribed psychotropic drugs using ATC codes. Crude and adjusted Cox regression models produced hazard ratios (HR) with 95% confidence intervals (CI) to estimate the association between parental PE and adolescents’ mental health. RESULTS: Adolescents with parents in PE exhibited a higher risk of developing mental disorders. The association was more pronounced for paternal PE (HR 1.22, 95% CI 1.10–1.35) compared to maternal PE (HR 1.11, 95% CI 1.00–1.21). These associations largely persisted after adjusting for important confounders, including parental mental health. CONCLUSION: This study addresses a significant gap in the literature on parental PE and adolescents’ mental health. As PE is growing more common across countries, this study provides relevant insights into the intergenerational role that parental low-quality employment may have in terms of mental health within families.