Dietary malic acid (MA) can be used to activate the rumen and participate in fatty acid conversion, which are promising techniques for ruminant nutrition. Therefore, the presented study evaluated the effects of malic acid supplementation on lambs' performance, biochemical, antioxidant status, and rumen fermentation. A total of 30 Barki lambs were randomly assigned to three groups. (i) C, served as the control group. (ii) 0.5% MA and (iii) 1% MA were supplemented with 0.5% and 1.0% malic acid of dry mater, respectively. The results reported that the low dose of MA (0.5% MA) had the highest values of the digestion coefficients of nutrients and a significant increase in the cell wall constituents compared to 1% MA and C. Furthermore, the 0.5%MA was significantly higher nutritive values, including nitrogen consumption, TDN and DCP parameters. In addition, there was a significant decrease in ammonia nitrogen content, NH3-N, while the VFA's were significantly higher in the 0.5% MA than in the C. However, the T3 and T4 concentrations were significantly higher in the 1% MA and 0.5% MA compared to C after 1, 3, and 6 h/day of MA treatment. Also, the GSH-Px concentrations were significantly higher in the 1% MA compared to C and 0.5% MA after 1 and 3 h of MA supplementation. It could be concluded that supplementation with 0. 5% MA of the dry matter improves lambs' performance, biochemical and antioxidant status, and rumen fermentation.