Providing stable conditions in various sectors of economy is one of the most important factors that is required for moving toward sustainable growth and holistic development in a country. One of the major prerequisites of economic stability and exiting the economic crises is financial stability. In economic literature, it is always emphasized on establishment of stability and sustainable growth via financial development. However, financial development requires financial tools such as an efficient banking system whose efficiency is possible through competitiveness and financial liberalization. The present study explores financial stability and economic performance in OPEC countries during the time period 2000-2013. It is applicable from objective aspect and descriptive-analytical from methodological aspect. It explores the relationship between financial sector and economic performance using the generalized method of moments (GMM) following Creel et al. (2014). The results disclosed that the effect of independent variable of financial stability on the dependent variable of economic performance (economic growth) in OPEC countries is positive and significant. This showed that increasing of financial stability and departing from financial crises decreases the investment risk and it is increased when transaction costs, production, and economic growth are increased in these countries. Likewise, the results demonstrated that the effect of the independent variable of financial liberalization on the dependent variable of economic performance (economic growth) in OPEC countries is positive and significant. This indicated that increasing of financial liberalization and improvement of financial transactions among countries will decrease the investment risk and it is increased when transaction costs, production, and economic growth are increased.