An experiment was conducted to study the effects of Tremella fuciformis ferment substance (TFS) supplementation in diets on the growth performance, fat deposition, blood lipids, and mRNA expression of lipid storage-related enzymes in the liver and adipose tissue of finishing pigs. Twenty eight-week-old pigs (10.03±0.59 kg) were randomly allocated to two dietary treatments: maize-soyabean meal-based diets with (TFS group) and without TFS (control group). The results of the experiment indicate that compared with the control group, the TFS diet led to a significant increase in the average daily gain and feed conversion ratio of pigs weighing 10 to 100 kg. However, the average backfat depth and leaf lard weight were not affected by TFS. Ingestion of TFS specifically decreased the serum triglyceride and glucose concentrations, but did not change the levels of total cholesterol and free fatty acids in the serum. The mRNA expressions of fatty acid synthase (FAS) and acetyl CoA carboxylase (ACCα) in the liver were down-regulated by dietary TFS. Conversely, the gene expressions of FAS and ACCα in the adipose tissue increased. The mRNA level of carnitine palmityl transferase-I (CPT-I) in adipose tissue was also increased by TFS. These results suggest that the addition of TFS at a dose of 4 g kg^-1 improves growth performance and lowers lipid metabolism in finishing pigs.