Nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated steatotic liver disease (MASLD) are significant public health concerns, with NAFLD being the most common cause of hepatocellular carcinoma in the Western world. The gut-liver axis, which involves the bidirectional interaction between gut microbiota and the liver, plays a crucial role in the pathogenesis of NAFLD/MASLD. Gut dysbiosis, characterized by alterations in the composition and diversity of gut microbiota, is a key factor in the development of these conditions. Probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT) are potential therapeutic options for NAFLD/MASLD, particularly for lean patients who have limited treatment options. However, the efficacy and safety of these interventions require further large-scale studies. Probiotics, such as *A. muciniphila* and *F. prausnitzii*, show promise in improving NAFLD/MASLD through their anti-inflammatory and metabolic effects. Genetically engineered probiotics aim to enhance the effectiveness of probiotics by ensuring stability in the gastrointestinal tract. Phages, or bacteriophages, have also been explored as a potential treatment for NAFLD/MASLD, but safety concerns and technological challenges remain. Prebiotics, which promote the growth of beneficial gut microbes, and synbiotics, combinations of probiotics and prebiotics, have shown some efficacy in reducing de novo lipogenesis and improving NAFLD/MASLD. FMT has been documented to restore gut dysbiosis and improve liver function in NAFLD/MASLD patients, especially lean ones. Despite these advancements, more research is needed to fully understand the efficacy and safety of these interventions.Nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunction-associated steatotic liver disease (MASLD) are significant public health concerns, with NAFLD being the most common cause of hepatocellular carcinoma in the Western world. The gut-liver axis, which involves the bidirectional interaction between gut microbiota and the liver, plays a crucial role in the pathogenesis of NAFLD/MASLD. Gut dysbiosis, characterized by alterations in the composition and diversity of gut microbiota, is a key factor in the development of these conditions. Probiotics, prebiotics, synbiotics, postbiotics, and fecal microbiota transplantation (FMT) are potential therapeutic options for NAFLD/MASLD, particularly for lean patients who have limited treatment options. However, the efficacy and safety of these interventions require further large-scale studies. Probiotics, such as *A. muciniphila* and *F. prausnitzii*, show promise in improving NAFLD/MASLD through their anti-inflammatory and metabolic effects. Genetically engineered probiotics aim to enhance the effectiveness of probiotics by ensuring stability in the gastrointestinal tract. Phages, or bacteriophages, have also been explored as a potential treatment for NAFLD/MASLD, but safety concerns and technological challenges remain. Prebiotics, which promote the growth of beneficial gut microbes, and synbiotics, combinations of probiotics and prebiotics, have shown some efficacy in reducing de novo lipogenesis and improving NAFLD/MASLD. FMT has been documented to restore gut dysbiosis and improve liver function in NAFLD/MASLD patients, especially lean ones. Despite these advancements, more research is needed to fully understand the efficacy and safety of these interventions.