This study focusses on imrpoving the mechanical performance of epoxy resin by reinforcing it with microcrystalline cellulose (MCC). Epoxy composites with varying MCC mass fractions (0.5%, 1%, 1.5%, and 2%) are prepared and characterised to assess the influence of MCC on strain-rate-dependent flexural properties, impact resistance, and nonlinear viscoelastic behaviour. Three-point bending tests at different strain rates reveal that MCC notably increases the flexural strength and leads to nonlinear mechanical behaviour. It is shown that stiffness, strength and elongation at break increase with rising MCC content. Charpy impact tests show improved energy absorption and toughness, while Dynamic Mechanical Analysis (DMA) demonstrates that the materials prepared exhibit increased storage modulus and improved damping across a frequency range. These results indicate that MCC serves as an effective bio-based reinforcement, significantly boosting the strength and toughness of epoxy composites. The findings contribute to the development of sustainable, high-performance materials for advanced engineering applications.