Despite its important implications child development, perfectionism has largely been ignored as an explanation for emotional diseases. We examined mediation models in which high levels of external pressure predict depression and anxiety symptoms, which may be mediated by low levels of self-exigency and high levels of negative self-evaluation. A sample of 2537 Spanish children completed the Child Perfectionism Inventory and the Clinical-Educative Questionnaire: Anxiety and Depression. The results indicated a predictive effect of external pressure on anxiety and depression symptoms, which was mediated by both low self-exigency and high negative self-evaluation. Our results suggest that dimensions of perfectionism play a critical role in psychopathological symptoms. Therefore, we recommend an increased focus on external pressure, self-exigency and negative self-evaluation to provide a better understanding of child psychopathologies.