The focus of this study is on the development and performance evaluation of sustainable Curauá/Areca hybrid fibre composites reinforced with epoxy and treated with alkali (NaOH) and nano-SiO₂. This work aims to enhance the mechanical and tribological efficiency of natural fibre composites through surface modification and nanoparticle incorporation, addressing the need for eco-friendly alternatives to synthetic composites. Optimization of the Curauá:Areca fibre ratio, NaOH treatment duration, nano-SiO₂ content, and applied load (for wear) was carried out using the Response Surface Methodology (RSM) for the mechanical and tribological processing parameters. Tensile and flexural strengths improved with higher Curauá fraction, while Areca-rich laminates displayed greater impact toughness. NaOH treatment increased fibre–matrix adhesion and was responsible for higher strength, less fibre pull-out, and reduced matrix porosity. Performance improved notably with nano-SiO₂ at intermediate loadings (~ 3–4 wt%), but decreased at higher loadings due to agglomeration. Tribological properties were best at 67% Curauá, 24 h NaOH treatment, ~ 3.75 wt% SiO₂, and 10 N load, with reduced wear rate and coefficient of friction attributed to the improved Curauá content, NaOH treatment, and optimum nano-SiO₂ dispersion. SEM analysis confirmed the results, illustrating enhanced fibre–matrix bonding, reduced fibre pull-out, and smoother wear surfaces in the treated, Curauá-rich composites. Under optimized conditions, RSM predictions were consistent with the experimental findings: tensile strength of 61.2 MPa, flexural strength of 76.3 MPa, impact strength of 20.2 kJ/m², minimum wear rate of 0.0011 mm3/Nm, and a coefficient of friction of 0.27. The novelty of this study lies in integrating alkali treatment and nano-SiO₂ reinforcement in Curauá/Areca hybrid composites to achieve superior strength and wear resistance, demonstrating a sustainable route for high-performing bio-composites.