The increasing globalization of business activities and the expansion of multinational enterprises have intensified challenges associated with corporate tax base erosion, profit shifting, and declining corporate tax revenue efficiency across jurisdictions. Despite international efforts to reform the corporate taxation framework, evidence remains limited regarding the extent to which Global Minimum Tax Reform can improve corporate tax revenue mobilization, particularly when comparing OECD and developing economies. This study examined the effect of Global Minimum Tax Reform on Corporate Tax Revenue Mobilization: Evidence from OECD and Developing Economies.  The study adopted an ex-post facto research design using a comparative panel data approach. Secondary data covering OECD and developing economies were analyzed using descriptive statistics, correlation analysis, and panel regression techniques. The Hausman specification test was conducted to determine the appropriate estimation model between fixed-effects and random-effects approaches. The findings revealed that Corporate Tax Base Protection Mechanism has a positive and significant effect on Corporate Tax Revenue Efficiency, indicating that stronger measures against profit shifting and tax base erosion enhance corporate tax revenue mobilization. The study also found that Effective Tax Rate Harmonization significantly improves Corporate Tax Revenue Efficiency by reducing harmful tax competition and strengthening international tax coordination. The study recommends that governments strengthen corporate tax administration systems, improve international tax cooperation, and develop effective mechanisms for implementing Global Minimum Tax standards. Developing economies should receive technical support to enhance institutional capacity and maximize the revenue benefits of global tax reforms.

Keywords: Global Minimum Tax Reform, Corporate Tax Base Protection Mechanism, Effective Tax Rate Harmonization, Corporate Tax Revenue Efficiency.