Bamboo is a widely used renewable and degradable biomass material; however, its sustainable utilisation is hindered by its susceptibility to mold. The current bamboo anti-mold technology is mainly based on organic chemical agents; these agents can easily induce mold resistance with long-term use, albeit some of these chemical agents have poor environmental performance, which in turn adversely affects human health. In the present study, a strategy of soap-free emulsion polymerisation was adopted to prepare poly(N-isopropyl acrylamide) (PNIPAm)/Citral nanohydrogel by encapsulating natural antibiotic of Citral in PNIPAm, followed by anti-mold treatment of bamboo. Results revealed that this nanohydrogels exhibit a core–shell system which Citral as the ‘core’ and PNIPAm as the ‘shellʼ. After the high-pressure impregnation of nanohydrogel, the control efficacy of bamboo against common bamboo molds, reached 100%, with the required concentration of PNIPAm/Citral being >6 times lower than that of unencapsulated Citral.