The government’s lockdown and restriction measures on the COVID-19 pandemic adversely altered livelihoods, commodity/food prices as well as food security status in Nigeria, especially for rural farming households. A multistage sampling technique was used to collect data from 480 rural farming households across three selected states of the SouthWest geopolitical zone of Nigeria. This research entailed rapid evaluation of the determining factors of rising food expenditure, implications for food security as well as households’ coping strategies during the COVID-19 pandemic. A structured questionnaire was used to obtain data that were analyzed using the following descriptive and inferential statistics: double-logarithmic analysis, Foster–Greer–Thorbecke (FGT) and probit regression analysis. The results showed that 60% of respondents were married, mean years spent in school was 17, mean age was 49 years, household size was 7 people and monthly income less than $200. The FGT model results for head count ratio showed that 78% of households were food insecure. The depth of food insecurity and severity before COVID-19 were 18.4% and 9.9% respectively, and 27.1% and 13.0% during the pandemic. The double-logarithmic regression revealed that household income, size, age and occupation significantly influenced the household’s food expenditure. Probit regression showed that households’ income, size, amount spent on food, and the household’s head, gender and educational level influenced its food security status. The research concluded that food security was indeed influenced by the COVID-19 pandemic among rural farming households in Nigeria. Intervention policies are needed to promote and enable sustainable livelihoods to eradicate hunger and food insecurity due to high food prices and high household sizes in relation to their low average income to enable rural farming households to economically recover and have the capacity to sustain themselves against future shocks.