COVID-19 is a pandemic disease which has caused fears and concerns among many people, with a significant influence on social and mental well-being. Considering this, this study investigated the impact of COVID-19 pandemic lockdown on social and mental health of Ondo State residents, Nigeria. Descriptive survey design was used in this study. Using multistage sampling technique, data were obtained through administration of questionnaire on 648 married couples with children in Ondo State. Data collected were analysed using inferential statistics. Findings revealed that respondents disclosed that their income and earnings have drastically reduced (X̄ = 2.89), feel withdrawn from community participation (X̄ = 2.96), reduced their interaction with people (X̄ = 2.98), reduced their interaction with their loved ones (X̄ = 2.67). The impact of COVID-19 lockdown on the mental health of the residents indicated that majority of the respondents feel lonely due to COVID-19 lockdown (X̄ = 3.00), feel distressed (X̄ = 2.87) and agitated (X̄ = of 2.47). The study revealed a significant difference in the social and mental health of Ondo state residents based on their age and gender; F (5, 642) = 10.554, p<.05, ɳ2 =.076; F (5, 642) = 6.694, p<.05, ɳ2 =.000 respectively. Hence, the impacts of the COVID-19 lockdown on the social and mental health of majority of the respondents was obvious. Therefore, health education awareness raising activities on mass media should be urgently conducted with focus on how people can cope effectively with their social and mental health during this lockdown period.
 
