As globalization and trade liberalization have increased integration of the world economy through financial and trade flows, the role of FDI and trade on economic growth is becoming more influential. This paper investigates the impact of FDI on trade of the East Asian economic transition countries, namely the China, Cambodia, Lao PDR, and Vietnam, employing FDI flow and FDI stock data separately. The data from these four countries during the period 1990–2019 have been collected, and OLS and panel within fixed effect estimators are utilized. The main findings show that, first, when estimated using FDI flow as independent variable, there exists complementary effect between FDI and trade, and the coefficients are significant except for Cambodia. Second, when estimated using FDI stock as independent variable, the impact of FDI decreases and even substitutability effect is found in China at significant level. Third, in both cases, the coefficient of FDI is shown positive and significant in Vietnam. In addition, the paper finds the effects of human capital, GDP, and WTO accession on trade are positive, while the effects of exchange rate, financial development, and tariff rate vary among the East Asian economic transition countries.