With the increase in the cognizance toward the wide and abundant lignocellulosic biomass, a great interest has been garnered toward the production of value-added products from the biomass. Hence, by capitalizing the Casuarina equisetifolia biomass, the current work developed a simultaneous pre-treatment and saccharification (SPS) process using transgenic Trichoderma atroviride. The ability of T. atroviride to produce lignolytic and cellulolytic enzymes was enhanced by optimizing key process parameters. Under the optimized conditions, a maximum of 1245.6 U/kg of cellulase and 1203.36 U/kg of xylanase, 183.2 U/kg of laccase along with 392.36 g/kg of fermentable sugars were obtained. On comparing with acid and alkaline pre-treatment methods, the T. atroviride -mediated SPS process exhibited trace formation of fermentative inhibitors, which resulted in a minimal inhibition of Escherichia coli. Overall, the current work implements the biorefinery concept on Casuarina equisetifolia biomass by advocating circular economy. Implications: Valorization of lignocellulosic waste biomass into value added compound and as biofuel is considered as a promising alternative resource, owing to its availability and low production cost. However, the presence of chemically resistant lignin demands an intensive treatment process, which sometimes leads to the formation of fermentative inhibitors. Casuarina equisetifolia is a deciduous commercial plant, and an average of 125 tonnes/hector of waste is generated annually in India. By considering the demerit of delignification and the wide availability of Casuarina equisetifolia biomass (CB), the current work aimed at the development of a single-pot simultaneous pre-treatment and saccharification (SPS) of CB by transgenic Trichoderma atroviride.