Nigeria, a fast-growing country has been food insecure prior to Covid-19 pandemic. Local agricultural production cannot satisfy the food and nutrition needs of its ever-growing population. This state was aggravated by the covid-19 pandemic lockdown, which was adopted by the Government to stem the spread of the virus. To cushion the effects of the lockdown, social assistance of diverse forms, from varying sources were supplied. This study assesses the effect of the lockdown order on household food security level and what coping strategies were adopted. Also, it examined the kinds of social assistance received and how such mitigated food insecurity status in households that benefitted. We used a secondary dataset from the Nigeria COVID-19 National Longitudinal Phone Survey. The data was collected by the National Bureau of Statistics in March, June, and July targeting periods before, during, and when the lockdown was gradually eased respectively. Our results revealed that majority of households experienced different forms of shock during the lockdown, most notably increase in food prices, and disruption of farm activities. Furthermore, only few households received social assistance majorly from state governments and religious bodies, such assistance had a positive effect on household food security during the lockdown period.