Due to the current energy crisis and environmental deterioration, there is a strong interest in the production of bio-ethanol from sustainable lignocellulosic biomass as an alternative renewable energy source. However, the availability of bioethanol at the commercial level is limited by factors such as the recalcitrant nature of the feedstock. Thus, effective pretreatment of biomass is required to improve cellulose accessibility and enhance acid hydrolysis. In this study, dry alkaline ball milling assisted deep eutectic solvent pretreatment was optimized via Box-Behnken experimental Design in Design expert software version 13.0.5. Compositional analysis was performed for both untreated and pretreated mango peels with NREL and ASTM protocols. The morphological structures for both untreated and pretreated samples at optimal conditions were characterized using FTIR, XRD, and SEM. The total reducing sugar after optimal hydrolysis were determined by the DNSA method. Statistical and regression analysis on the experimental outcomes revealed that the lignin removal and reducing sugar recovery follows second-order nonlinear equation and quadratic models were developed to validate the model. It was found that the mango peel has a proximate composition containing moisture content of 10.01±0.7%, ash content of 4.3±0.88%, volatile matter of 4.3±0.88%, and fixed carbon content of 14.67±1.4% and chemical composition shows cellulose content of 32.14%, hemicelluloses of 20.42%, and lignin content of 25.23%. After pretreatment, the cellulose composition increased to 68.27%, and the lignin content decreased to 2.3 % at optimal conditions. The design expert under numerical optimization gave optimal values test factors were a milling time of 42.791 min, an alkaline concentration of 3.031%, a rotational speed of 260.597 rpm, and a solid-to-liquid ratio of 1:15.6%w/v. At those optimized parameters a lignin removal of 87.868% and a reducing sugar recovery of 59.760% g/g sugar were achieved with the desirability of 95.7%. The model result obtained from the experiment the lignin removal and reducing sugar were 95.4106±0.02% and 62.53±0.01g/g sugars respectively. The maximum yield of the bioethanol was 56% fermentation time of 72 hours with %purity of 88.6%. The physical properties of produce bioethanol (Specific gravity of 0.8915, density of 0.8942 g/cm3, pH value of 6.79, flash point of 19.2 ℃ and viscosity of 1.49 mm2/s) were very close to the standard. The finding from this research shows that fruit peels like mango can be used to produce bioethanol by using effective pretreatment such as dry alkali ball milling assisted deep eutectic solvent intensified treatment. Keywords: Ball milling, DES solvent, Alkali treatment, Bioethanol, Mango peel