This study sought to determine the moderating effect of company size in the effect of corporate governance mechanism on corporate social responsibility disclosure of listed manufacturing companies in Nigeria. The study adopted a post-positivist research philosophy and expost factor research design was used. Secondary data was obtained from financial statements and accounts of listed manufacturing companies from 2010 to 2022 using disclosure check listed adopted from previous studies. The collected data was converted into excel format for easy arrangement into panels. The estimation of the relationship between the variables of the study was achieved using E-view version 10 statistical software. As a panel data, ordinary least square was used to identify the regression model with the highest explanatory power. Findings of the study revealed that company size positively and significantly moderate the effect of corporate governance mechanism on corporate social responsibility disclosure of listed manufacturing companies in Nigeria. The study recommended that corporate affairs commission and the manufacturers association of Nigeria should put up adequate regulatory framework and guidelines to ensure more disclosure of corporate social responsibility activities of the manufacturing sector is achieved Nigeria.