The COVID-19 pandemic caused a major crisis in numerous social spheres, especially among children, due to the closure of schools in hundreds of countries. The lockdown resulted in classes being given exclusively online, which could have led to increased participation in antisocial online behaviour such as cyberhate. This research aims to find out the impact of lockdown on cyberhate in children in Primary Education and to analyse the role of social, emotional and moral competencies as a protective factor. The study was conducted with 792 primary school pupils (Mage=10.81, SD=0.85) from Cuenca (Ecuador). A questionnaire focusing on cyberhate, social and emotional competencies, empathy, and moral emotions scales was used. A quantitative study was carried out with a longitudinal design with two data rounds of collection separated by an interval of five months. The results showed that total cyberhate and its dimensions, perpetration and propagation, increased longitudinally. Cyberhate among these participants could be predicted, after five months of lockdown, for being male, being in the highest school year, attending a state school, and obtaining low scores in moral emotions. The effects of the lockdown have highlighted the importance of face-to-face social relationships, which has exciting implications on the importance of school in developing social, emotional, and moral competencies which foster coexistence and respect for diversity.