This study aims to analyze economic growth and its determinants in the ASEAN-9 region using a quantitative approach within a macroeconomic production function framework. Annual panel data from 2008 to 2024 are utilized to capture both temporal and cross-country variations among the nine ASEAN member states. The analysis is conducted using Stata software through panel data regression with a fixed effect model to control for unobserved heterogeneity. The input variables include Gross Fixed Capital Formation, Labor Force Participation Rate, Electric Power Consumption, Trade (% of GDP), and General Government Final Consumption Expenditure, while the output variables are represented by GDP, GDP Growth, GDP per Capita, and GDP per Capita Growth. The results indicate that Gross Fixed Capital Formation significantly and positively affects economic growth, while the Labor Force Participation Rate is significant only for aggregate GDP. Electricity consumption per capita shows a positive effect on GDP levels but a negative effect on growth, reflecting inefficiency in energy use. International trade negatively influences GDP but positively affects growth, whereas government consumption expenditure has a significant negative effect on growth. Overall, the findings demonstrate that the efficiency of economic growth in the ASEAN-9 is shaped by the quality of investment, labor productivity, energy efficiency, and fiscal policy effectiveness, implying that governments should promote productive investments, enhance human capital, and direct energy and fiscal policies toward inclusive and sustainable economic development.