Obesity and related disorders are a common cause of morbidity worldwide. Nonalcoholic fatty liver disease is the most important hepatic consequence of adipose accumulation. There is strong evidence of obesity-related disorders as risk factors for hepatocellular carcinoma and of nonalcoholic fatty liver disease as a cause of hepatocellular carcinoma, but it is apparently less important than other chronic liver diseases. Unfortunately, preventive measures are not well validated in the population of patients with NAFLD. In this review, we analyze the available information supporting the increased risk of hepatocellular carcinoma in obese patients and patients with nonalcoholic fatty liver disease, considering the epidemiological and basic research-derived evidence.