This research looked into the relationship between transactions costs and agricultural household supply response with a focus on maize farmers in Oyo and Osun States of Nigeria. The research specifically analyzed the quantity of maize supplied by respondents and factors determining such quantity. Multistage random sampling technique was employed to sample four hundred maize producing farmers for the study. A structured interview schedule was used to collect primary data from the respondents. Data collected were analyzed using descriptive statistics and estimation of Cobb-Douglas regression model. Costs and returns analysis, as well as the Chow's F-test, were also used. Nine independent variables were estimated to determine their level of relationship with the quantity of maize supplied. The independent variables were price of maize (X1), area of land cultivated to maize (X2), Negotiation Cost (X3), Agents fee (X4), Harvesting cost (X5), Assemblage cost (X6), Storage cost (X7), Transportation cost (X8) and Transactions land rent (X9). Data analysis showed that significant relationships exist between transactions costs and agricultural household supply response in the study area.