The study investigated into the effect of cost management on financial performance of manufacturing firms in Nigeria. The specific objectives include to examine the cost of inventories, cost of labour, and cost of sales on performance. The study will be relevant for investors, management board and regulatory bodies. Thhe study employed the descriptive research design. The study employed panel data covering four (4) years 2014-2018 which was gathered from the financial statement of selected manufacturing firm. The study employed the pooled regression analysis for the study in testing the hypothesis. The study conceptual framework of the study covered the following concept; cost management, cost management strategies and financial performance. The theoretical framework includes; Cost management& Efficiency Theory, Theory of constraints and Transaction cost Economics Theory. The study revealed that cost of inventories has positive insignificant effect on return on equity. Cost of labour has negative significant effect on return on asset. Cost of inventories, cost of labour, and cost of sales has negative insignificant, negative insignificant and positive significant effect on size (performance).