This study examined how foreign direct investment (FDI) affect economic growth in Nigeria and Ghana for the period 1986 to 2023. While FDI can benefit a country, its impact depends on the country’s specific conditions and policies. The study had three main objectives: to examine the link between FDI and economic growth in both countries; to find out how trade openness influences economic growth; and to assess how exchange rates affect economic growth in Nigeria and Ghana. The data were sourced from the Central Bank of Nigeria (CBN) Statistical Bulletin (2023), and the Bank of Ghana (BOG) publications. The panel least squares regression was used in analyzing the data. The panel least square was preceded by the Levin Lin and Chu panel unit root test, Pesaran’s cross section dependency test, panel cointegration and Hausman specification test. The pre estimation results showed that the data were all stationary at first difference, and exhibited cross-section dependency. This implies that FDI policies in one of the West African country will affect the neighboring country. Also, the data were cointegrated and the estimation favored the random effect (RE) model. The results from the random effect estimates showed that FDI had a strong positive impact on economic growth in both countries. However, trade openness did not significantly affect growth, and exchange rates had a negative impact on economic growth. The study concluded that FDI has grown in the ECOWAS region, particularly in Nigeria and Ghana, and has contributed to their GDP growth. However, trade openness, especially in Ghana, remains a challenge. The study recommended that ECOWAS countries should promote trade, technology exchange, and innovation to attract more FDI.