Purpose <p>This study seeks to investigate the effect of green finance and financial technology on the development of financial institutions in the countries of the Organization for Economic Cooperation and Development (OECD). Furthermore, it examines the moderating influence of FinTech on the green finance in the financial institution development.</p> Design/methodology <p>Using panel data from the period 2013–2022, this study uses a fixed-effects model for the baseline estimation and endogeneity and sample selection bias by using the two-step system generalised method of moments (GMM), Two-Stage Least Squares and the Heckman selection model.</p> Findings <p>The results indicate that green finance and financial technologies positively effect financial institutions, and fintech contributes significantly to the growth of green finance. Moreover, the paper performed a disaggregated analysis of the green finance and heterogeneity analysis confirming the consistency of the findings. The results of heterogeneity analysis reveal that the roles of financial technologies and green finance are greater in lower<b>-</b>income countries. Additionally, green finance has a stronger impact in countries with low green finance adoption, and the marginal benefit of FinTech is more pronounced in countries with low FinTech adoption.</p> Practical implications <p>The results of the paper offer policymakers a detailed new insight into how green finance and fintech, and their interaction, drive financial institution development in OECD economies.</p> Originality/value <p>: To the best of authors’ knowledge, this paper is one of the few studies that empirically analyse the effects of financial technologies and green finance in developing financial institutions in the member countries of the OECD. In addition, various methodological approaches have been used to confirm the robustness of our results.</p>