At the moment, few therapeutic options are available for the treatment of NAFLD. To date, the most effective therapeutic approach for NAFLD is weight loss. In this line, bariatric surgery (BS), which produces marked reductions in body weight, is associated with significant histopathological improvements in advanced stages of NAFLD, including NASH and liver fibrosis. BS is also associated with substantial taxonomical and functional alterations in gut microbiota, which are believed to have a significant role in the metabolic improvement after BS. Moreover, emerging evidence highlights the potential association between gut microbiota changes after BS and NASH resolution.