Theory attributes finance with the ability to both promote growth and reduce output volatility. But evidence is mixed in both regards, partly due to endogeneity effects. For example, financial institutions themselves might be a source of volatility, as the events of 2008 suggest. We address this endogeneity issue by using oil price volatility as a source of exogenous volatility, to study the effect of finance. To do this, we use two empirical methodologies. First, we develop a quasi-natural experiment by studying the dramatic decline of oil prices in 2014 and beyond, using a synthetic control methodology. Our hypothesis is that the ability of oil-rich countries to mitigate the effects of this decline rested on the quality of their financial institutions. We focus on 11 oil-rich countries between 1980 and 2014 that had “poor” measures of financial development (treatment group) out of 20 such countries and synthetically create counterfactuals from the remaining (control) group with “superior” financial development. We subject both to the oil price shock of 2014. We find evidence that better financial institutions do indeed reduce output volatility and mitigate its negative effect on growth in the year that showed a sustained decline of the oil price. To address any remaining potential endogeneity between oil prices and finance, we further examine our findings by using a Panel CS-ARDL approach with 30 oil producing countries in our sample (and data over the period 1980-2016), illustrating that the effect of oil price volatility on growth is mitigated with better financial institutions. Our results make a strong case for the support of the positive role of financial development in growth and development.