This paper considers an alternate dimension of government institutions associated with the separation of powers between government and its central bank. A more independent central bank is consistent with greater institutional quality and constraints on government. We propose that central bank independence influences the prevalence of the shadow, or underground, economy. Using cross‐country panel data for over 100 nations over the period 1991 to 2012, the results from instrumental variables techniques show that central bank independence curbs underground economic activity. Furthermore, considering different dimensions of independence, we find that independence related to central bank CEO, policy formation, and central bank lending are effective at checking the shadow sector. Overall, these findings are robust to a different measure of the underground economy, correcting for the potential influence of outliers, controlling for the impact of additional factors, accounting for heterogeneity related to the level of development, and considering the heterogeneity related to the prevalence of the shadow sector. The main implication of the results is that nations seeking to reduce the prevalence of the underground economy would benefit from policies that promote central bank independence.