Abstract: To enhance the shelf life of fresh-cut bamboo shoots (Pleioblastus amarus), this study initially formulated three solutions: nano-selenium (SeNPs), functionalized nano-selenium (SeNPs-cs), and a combination of chitosan with functionalized nano-selenium (CS&SeNPs-cs). By characterizing these solutions and comparing their antioxidant activities, the most stable and effective antioxidant solution was selected for application in the preservation of fresh-cut bamboo shoots. The results indicated that the SeNPs were spherical particles with an average particle size of 88.63 nm and a ζ-potential of -3.84 mV. The average particle sizes of SeNPs-cs and CS&SeNPs-cs were 141.12 nm and 193.72 nm, respectively, with corresponding ζ-potentials of 4.2 mV and 35.8 mV. The synergistic interaction between SeNPs and chitosan (CS) significantly enhances the stability of the nano-solutions. At a concentration of 300 mg/L SeNPs, CS&SeNPs-cs exhibited the highest scavenging abilities against DPPH and ABTS⁺ radicals, with efficiencies of 75.54% and 47.98%, respectively. In preservation experiments, CS&SeNPs-cs treatment significantly reduced the weight loss and respiration rates, slowed the decline of soluble proteins and total sugars, inhibited the activities of polyphenol oxidase (PPO) and peroxidase, advanced the peak of catalase (CAT), maintained higher total phenol content, delayed color changes and browning, and suppressed microbial proliferation on the surface of fresh-cut bamboo shoots compared to chitosan (CS group) and water (CK group). In conclusion, CS&SeNPs-cs treatment effectively retards the deterioration of fresh-cut bamboo shoots and extends their shelf life.