This study investigates an alternative approach to addressing the water pollution problem caused by dye molecules. The presence of dye molecules in water systems tends to pose significant risks to human health and ecological systems under long-term exposure. Thus, the purpose of this study is to increase the efficiency of sunset yellow (SY) dye degradation utilizing a microcrystalline cellulose (MCC) derived from Dendrocalamus asper bamboo fiber-supported-TiO₂ composite photocatalyst assisted by UVC irradiation. MCC from bamboo can be utilized as reinforcement of bio-composite materials due to its high fiber content, low density, higher mechanical and tensile strength, and high biodegradability features when compared to other biomass materials. In this work, the photocatalysts were synthesized using a simple chemical mixing technique with different MCC to TiO₂ ratios (0.3:1, 0.5:1, and 0.7:1). They were characterized using Fourier transform infrared spectroscopy (FTIR) to determine their functional groups. The synthesis technique was designed to improve charge carrier separation and broaden light absorption, resulting in significant photocatalytic activity; rate constant was obtained by 2.33 × 10^-2 min^-1 associated with pseudo-first-order kinetics, surpassing the performance of pure TiO₂. The main reactive species were identified to be positive holes (h⁺) and hydroxyl radicals (•OH). This work revealed that the MCC-TiO₂ composite photocatalysts exhibit promising potential for degrading dye molecules via heterogeneous photocatalytic mechanism.