The combined effect of non-ionic surfactants with ammonia during pretreatment enhanced lignin removal and retained most cellulose, especially with Tween 80 (37%, 87%) and PEG 4000 (47%, 86%), respectively. Tween 80–dilute ammonia treated sugarcane bagasse resulted in the highest cellulose digestibility (66%). However, PEG 4000–dilute ammonia treated sugarcane bagasse had the highest ethanol concentration of 20 ± 1.1 g/100 g of dry biomass with a theoretical yield of 73%. SEM images revealed severe disruption of biomass structure. FTIR and XRD showed a change in crystallinity. An increase in thermal stability was observed by TGA.