Digitalization and technological innovations have fundamentally transformed the functioning of financial systems, giving capital markets a new direction and momentum. Financial Technologies (FinTech), which is at the heart of this transformation, is fundamentally reshaping investment decision-making processes, capital movements, and financial intermediation mechanisms. In this context, analyzing the impact of FinTech on portfolio investments in developing countries is important for understanding the implications of digitalization on financial markets. In this study, using annual data from 2011–2021, the relationship between FinTech scores and portfolio investments in developing countries was examined using the Emirmahmutoğlu and Köse (2011) panel causality test. According to the findings, no significant causality relationship from FinTech to portfolio investments was found at the panel level. However, when the results were examined on a country basis, a one-way causality relationship from FinTech to portfolio investments was found only in the Philippines. This finding is consistent with the Philippines' rapidly growing digital finance ecosystem in recent years. The results indicate the need to strengthen digital infrastructure, ensure the integration of FinTech applications with capital markets, and develop regulations that will increase investor confidence.