Foreign Direct Investment (FDI) is a critical engine of economic growth, innovation, and regional development, especially within emerging economies like those in the Association of Southeast Asian Nations (ASEAN). Despite ongoing efforts toward regional integration under the ASEAN Economic Community (AEC), FDI inflows from 2011 to 2020 remain markedly uneven across the ten member states. This study analyzes FDI trends, disparities, and determinants in ASEAN countries over a ten-year period, focusing on population size, income classification, and GDP growth as explanatory factors. The research employs a descriptive-comparative and correlational design using secondary data from reputable global databases. One-Way ANOVA confirmed statistically significant differences in average annual FDI inflows among member states, while Multiple Linear Regression revealed that population size and income status significantly influence FDI levels—unlike GDP growth, which showed no independent predictive power. Notably, Singapore accounted for 62.81% of ASEAN’s total FDI, while Brunei Darussalam and Lao PDR received less than 1% each. These findings suggest that larger markets and higher income classifications are more attractive to foreign investors. The study underscores the need for targeted national and regional strategies to address investment disparities by improving regulatory frameworks, infrastructure, and institutional stability. Recommendations include enhancing human capital, fostering inclusive development, and leveraging demographic strengths to attract sustainable FDI. Ultimately, this research contributes valuable empirical insights to support more balanced and effective FDI strategies across the ASEAN region.