This study examined how cost of sales influences the firm value of listed agricultural companies in Nigeria. An ex-post facto research design was adopted to analyze audited historical financial data collected from five listed Nigerian agricultural companies, including Ellah Lakes PLC, FTN Cocoa Processors PLC, Livestock Feeds PLC, Okomu Oil Palm PLC, and Presco PLC, which were selected by census sampling. The secondary data obtained from the annual reports of the firms under investigation was from the period of 2015 to 2024. Hypotheses were tested using panel estimated generalized least squares. The findings revealed that cost of sales had a significantly positive effect on firm value (β = 8.801653, p = 0.0000), indicating that effective management of production and operational costs enhanced financial returns. Therefore, the management of listed agricultural companies was advised to strengthen structured cost management practices that focused on efficient procurement of raw materials, improved inventory control, and optimized production processes, so that spending on cost of sales continued to support the growth of revenue and translate into higher firm value rather than generating unnecessary operational waste.