Pretreatment is a necessary step in the process of biorefinery of lignocellulosics. Here, a novel sequential sugarcane bagasse (SCB) pretreatment method was developed based on potassium peroxymonosulfate (PMS) and alkaline deacetylation (AD) under mild conditions. The co-pretreatment could efficiently remove the lignin and acetyl groups, resulting in a holocellulose-rich (83.5%) solid with superior degradability and a high overall recovery of holocellulose (81.2%). Meanwhile, the highest ethanol titer of 120.77 g/L and succinic acid production of 34.84 g/L were obtained by simultaneous saccharification and co-fermentation (SSCF) without the sterilization process for the pretreated SCB (equivalent to an ethanol yield of 0.36 g/g and a succinic acid yield of 0.10 g/g from the holocellulose in raw SCB). These results demonstrated that a high level of bioethanol and bio-based succinic acid can be achieved by the combination of the newly-developed SCB pretreatment method and the robust yeast strain.