We examine the impact of foreign direct investment (FDI) on financial inclusion. To identify the causal effect of FDI on financial inclusion, we use plausibly exogenous source of variations in bilateral investment treaties (BITs) as a novel instrumental variable (IV) for net FDI inflows. Using annual data for a broad panel of 90 countries over the period 2004 to 2017, our results show that FDI improves financial inclusion for both “access to finance" and “use of financial services". This impact is more pronounced for relatively poor countries and developing countries compared to rich and developed countries. We also find that higher financial market development and quality institutions improve financial inclusion directly. Moreover, financial market development and institutional quality can serve as potential channels and moderating variables through which FDI affects financial inclusion. Our results are robust to various estimations and sample splitting and have important implications for policy on financial inclusion.