Foreign direct investment (FDI) inflows to Vietnam have increased significantly in recent years. Theoretically, capital inflows will put pressure on the overvaluation of local currencies in countries, despite different exchange rate mechanisms. So, the problem facing the Vietnamese government is the need to examine the relationship between the exchange rate and FDI in order to develop effective policies. This study examined the relationship between the exchange rate and FDI in Vietnam in the period of 2005–2019 using the VAR (vector autoregression) model based on quarterly frequency data. The new points of this study are: (i) using the real effective exchange rate (REER) of the Vietnamese currency with 143 major trading partners of Vietnam; and (ii) adding two control variables into the VAR model to examine the relationship between the exchange rate and FDI in Vietnam – a case study for developing countries. The findings show that, firstly, there is a positive causal relationship between FDI and Vietnam’s real effective exchange rate. Secondly, trade openness has a positive impact on FDI and REER in Vietnam. Thirdly, economic growth has an impact on REER, but no statistically significant impact on FDI was found. The findings can provide useful information to help policymakers plan and make decisions on future policies and support further research studies.