Consumption of phytosterols is a nutritional strategy employed to reduce cholesterol absorption, but recent research shows that their biological activity might go beyond cholesterol reduction for the treatment of metabolic dysfunction-associated fatty liver disease (MAFLD), and novel phytosterol formulations, such as submicron dispersions, could improve these effects. We explored the therapeutic activity of phytosterols, either formulated as submicron dispersions of phytosterols (SDPs) or conventional phytosterol esters (PEs), in a mouse model of MAFLD. MAFLD was induced in mice by atherogenic diet (AD) feeding. The reversion of distorted serum and liver parameter values after a period of AD feeding was investigated after supplementation of the AD with SDPs, PEs, or a placebo (PT). Additionally, the metabolic parameters of fatty acid synthesis, fatty acid oxidation, and inflammation were studied to understand the mechanism of action of phytosterols. AD supplementation with SDPs was shown to reduce liver fat, along with showing a significant improvement in liver triglycerides (TGs), free fatty acids (FFAs), and liver cholesterol levels. These results were reinforced by the analyses of the liver steatosis scores, and liver histologies, where SDP intervention showed a consistent improvement. Treatment with PEs showed slighter effects in the same analyses, and no effects were observed with the PT treatment. Additionally, SDP intervention reversed, with a higher efficacy than PEs, the effect of AD on the serum levels of TGs, total- and LDL-cholesterol levels, and glucose levels. And, exceptionally, while SDP improved HDL-cholesterol serum levels, PEs did not show any effect on this parameter. We provide evidence for the therapeutical activity of phytosterols in MAFLD beyond the regulation of cholesterol levels, which is increased when the phytosterols are formulated as submicron dispersions compared to ester formulations.