The production of isopropanol and butanol (IB) has been gaining attention through isopropanol-butanol-ethanol (IBE) fermentation. In this work, the substrate inhibition and butanol tolerance of Clostridium beijerinckii DSM 6423 in isopropanol-butanol (IB) production by isopropanol-butanol-ethanol (IBE) fermentation from an industrial mixture of sugarcane and sweet sorghum juices were assessed. The results showed that an initial sugar concentration of 40 g/L in the industrial juices showed the best kinetic for the fermentation. The formulation of a low-cost medium for IB production from industrial juices by C. beijerinckii DSM 6423 was also studied. Corn steep liquor (CSL), a byproduct of the wet milling of corn, could serve as a nutrient of low cost and replace both yeast extract and vitamin complex without significantly affecting the production of butanol and isopropanol. A CSL concentration of 5 g/L was shown to be adequate to achieve the best results. C. beijerinckii DSM 6423 produced 5.3 and 7.9 g/L of isopropanol and butanol, respectively, with a sugar conversion of 93%. This work provides valuable insights into cost-effective nutritional supplementation of industrial juices for IB production.