Abstract: This research looked into the relationship between transactions costs and agricultural household supply response among maize farmers in Osun state. Multistage random sampling technique was employed in selecting 180 respondents for the study. A structured interview schedule was used to collect data from the respondents. Data were analyzed using descriptive statistics and an estimation of Cobb-Douglas regression model. The descriptive analysis revealed mean age of respondents as 42.7 years while 93% were married. It further showed that 52.2% of the farmers depended on personal savings in financing their maize production activities while only 14.4% of them received no formal education at all. Adjusted R² for the regression analysis was 0.734 showing that 73.4% of the variation in quantity of maize supplied by respondents was explained by the estimated variables. Data analysis showed that significant relationships exist between transactions costs and agricultural household supply response in the study area. The study concluded that in addition to price factor, transactions costs contribute significantly to agricultural household supply decisions and consequently recommends that policies that reduce transactions costs should be formulated and implemented to serve as compliments to various price policies in ensuring adequate returns to farmers’ investment and stimulate expansion in food production, thereby enhancing the level of food security in Nigeria.