AbstractAcid dyes are often used to improve the decorative properties of bamboo products. However, the use of these dyes is problematic because they run easily. This study examined the use of chitosan as a fixing agent to address this issue. The study also investigated the interaction between dyed bamboo powder and dyed veneers pre-treated with chitosan. Powder was dyed at various pH values with acid scarlet GR and soaked in various solvents. Analyses were conducted using Fourier transform infrared spectroscopy, a zeta potential measurement analyzer, UV-visible spectroscopy, and a color measuring instrument. Pre-treated bamboo veneers were also dyed with acid scarlet GR and evaluated with the color measuring instrument, a scanning electron microscope, and an optical microscope. Chitosan functioned as a bridge and immobilized dye on the bamboo. This occurred through a chemical reaction and opposite charge attraction under acidic conditions. Pretreated dyed bamboo veneers demonstrated excellent dye uptake, color-fastness, and levelness. Therefore, chitosan shows promise for use as a fixing agent in dyed bamboo.