Areca palm stem fiber reinforced epoxy composites modified with alkaline surface treatment and nano alumina were investigated to evaluate improvements in physical and mechanical performance. Composite laminates were fabricated by the hand layup method with 20 wt. % areca palm stem fiber, while sodium hydroxide treatment levels (0, 3, 6, and 9 %) and nano alumina loadings (0, 2.5, 5, and 7.5 wt. %) were varied. The fabricated composite specimens containing 5 wt. % nano alumina, subjected to varying treatment concentrations, consistently exhibited reduced void content and enhanced density. Mechanical characterization showed a significant enhancement in strength and toughness due to the combined effects of fiber surface activation and nanoparticle reinforcement. A 6 % NaOH treatment with 5 wt. % nano alumina resulted in a 53.60 % increase in tensile strength and a 43.05 % increase in flexural strength compared to untreated composites. Maximum impact energy (5.81 J) and hardness (59.5 HV) were obtained at 7.5 wt. % nano alumina with 6 % NaOH-treated fibers. Scanning electron microscopy revealed reduced fiber pull-out and improved interfacial bonding, though voids and microcracks were observed at higher filler loadings.