Both clinical features of seizures and affective problems (i.e., depressive and/or anxious symptoms) affect quality of life perception in patients with epilepsy. Although genetic generalized epilepsies (GGEs) represent one-third of all epilepsies, very few studies focused on the association among seizures, affective problems, and perceived quality of life in pediatric patients with GGE. Here, we assessed the relative contributions of seizure characteristics and affective symptoms on quality of life in patients with adolescence-onset GGE. Forty pediatric outpatients completed self-report questionnaires on affective symptoms and quality of life. Sociodemographic and clinical variables were obtained from medical charts. Affective symptoms were present in 40% of patients. Higher scores emerged in patients who were seizure-free at the time of the survey for both the physical and mental components of quality of life. Higher seizure frequency was significantly associated with lower quality of life scores in the mental component, whereas the presence of depressive and/or anxious symptoms was significantly associated with lower scores in the physical component. These associations were confirmed after controlling for sociodemographic confounders. These findings suggest that adolescents with GGE are at increased risk for affective symptoms. Moreover, both GGE-related clinical features (i.e., seizure frequency) and the presence of affective symptoms (i.e., depression, anxiety) are relevant and independent contributors to quality of life. The investigation of affective problems is warranted to be included in routine assessments of GGE in pediatric populations.