In this investigation, the influence of various plasma powers 80 W and 120 W for 30 min on mechanical as well as surface characteristics of unidirectional sisal fibers surface treated using cold glow discharge argon plasma had been explored. Agave sisalana is a rosette-forming succulent plant farmed primarily for its fibers, which have been extracted from the leaves. Sisal fibers possess low in compactness, ubiquitous, and environmentally friendly, although they typically exhibit problems such as hydrophilicity and performance. Per our observations, the cold glow discharge argon plasma modification provided the sisal fiber-reinforced epoxy composite (SFREC) with nearly 50.32% significantly greater interlaminar shear strength, 48.66% significantly greater flexural strength, 48.74% elongation at break, and 30.919% significantly greater tensile strength compared to the untreated sisal fiber-reinforced epoxy laminate. Overall morphological features for cold glow discharge argon plasma-treated sisal fibers had been compared to the untreated sisal fibers using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD), revealing an improvement in fiber surface structure. FTIR particularly revealed the influence of oxidation of basic constituents of the sisal fiber and/or a reduction of both phenolic and secondary alcohol groups leading hydrophobicity after the surface modification. Furthermore, XRD analysis reveals the cold glow discharge plasma Ar alteration increased crystallite size and crystallinity by eradicating some undesirable elements of the sisal fiber and rearranging the crystalline zones. Hence, sisal fibers might well be exploited for industrial application after becoming surface treated to accomplish the aim of fostering self-sustaining biodegradable natural resources.