This paper gives first empirical evidence from Vietnam, an emerging country, on the impact of financing decision on firm performance in Vietnam. The study uses data of 102 non-financial firms listed on Ho Chi Minh Stock Exchange (HOSE) in the 2008-2018 period. Generalized method of moment (GMM) is employed to overcome drawbacks of the model to assure stable and efficient findings. In this study, return on assets (ROA) is utilized to measure firm performance. Further, financing decision is measured by three indicators: total debt to total assets (TDTA), long-term debt to total assets (LTDTA), and short-term debt to total assets (STDTA). Besides, firm size (SIZE), economic growth (GDP) and inflation rate (INF) are also used as control variables. The paper reveals that firm performance is significantly correlated with financing decision. The findings confirm that the increase in debt use decreases firm performance. Therefore, it is recommended that firms should be chary of using debt to finance business operation as it can lead to bad effects on their performance. The results also report the positive effects of inflation rate on financial development. Accordingly, some strong implications are suggested in order that the authorities and management can develop suitable policies to improve firm performance and aim to a sustainable and steady development.