Since marine algal polysaccharides have long presented a wide range of bioactivities, there has been an interest in them as possible remedies for liver diseases. Algal polysaccharides can be used as antioxidant, anti-inflammatory, anti-apoptotic, detoxifying, and anticancer in nature, and they act to counter oxidative stress, inflammation, apoptosis, and metabolic disturbances, especially in cases of NAFLD. Pairwise molecular interactions to semi-molecular interactions occur between marine algal polysaccharides and two or three key cell signaling pathways (such as Nrf2, NF-κB, and PI3K/Akt), regulating gene and enzyme activity related to hepatic metabolism, detoxification, and tumorigenesis. Because of their hepatobiliary properties, they can also modulate the gut-liver axis when algal polysaccharides interact with the gut microbiota and decrease the extent of translocation of endotoxins. Regardless of the strong evidence in preclinical studies, there are limited trials in human populations, primarily due to the heterogeneity of components and the lack of optimized standardization protocols, which precludes their complete clinical use. Future studies should focus on refining extraction protocols, ensuring product consistency, and demonstrating efficacy through human studies. Additionally, exploring the synergistic potential of marine algae with existing products/drugs, facilitated by advancements in algal biotechnology, could enable the production of custom polysaccharide profiles for targeted liver therapy. Given their promising nature, marine algal polysaccharides may lead to the development of safe and effective agents for the prevention and treatment of liver diseases.