ObjectiveThis study examined the protective role of self-esteem and perceived emotional intelligence on mental health problems in Spanish adolescents during COVID-19 pandemic. MethodParticipants (N=139; Mage=13.83years; SD=0.96; 63.8% female) completed measures before the outbreak of COVID-19 (T1) and during the first wave of the pandemic in Spain (T2). Participants self-reported emotional intelligence, self-esteem, mental health problems and suicidal behavior. ResultsAdolescent mental health problems were equally affected by COVID-19 pandemic according to gender, age and lockdown conditions. Adolescents with low levels of emotional intelligence and self-esteem at T1 showed a significant decrease in self-reported anxiety, depression, stress and suicidal behavior at T2. However, adolescents with average or high levels of emotional intelligence and self-esteem at T1 showed no significant changes in mental health problems at T2. Self-esteem at T1 meditated the relationships between emotional intelligence at T1 (clarity and repair) and emotional symptoms at T2 (depression, anxiety and stress). Furthermore, the relationship between self-esteem and anxiety symptoms was moderated by the number of people living together during COVID-19 lockdown. ConclusionOur findings highlight the protective role of pre-pandemic development of self-esteem and emotional intelligence in mitigating the impact of COVID-19 outbreak on adolescent mental health during the pandemic.