Sustainable economic growth requires effective investment in physical capital, but the difference in performance between countries in this regard is due to the level of knowledge development and their economic institutions. However, a precise understanding of how knowledge and institutional components interact in the process of physical capital accumulation, especially in developing countries with diverse economic structures and specific institutional challenges, is a research gap. Identifying these relationships is essential for formulating effective policies to improve countries' physical capital accumulation. The purpose of the present study is to examine the impact of knowledge components, including domestic R&D accumulation, foreign R&D spillovers, human capital, and economic freedom, on physical capital accumulation in selected developing countries. The present study covers the period 2011-2022 using panel data and ordinary least squares estimation method. The results show that domestic R&D accumulation, foreign R&D spillovers, and human capital have a positive and significant effect on physical capital accumulation, while the effect of some components of economic freedom is only significant at certain levels of institutional development. The findings emphasize the importance of a knowledge-based approach in policymaking for the development of physical capital.