A novel biodegradable layered double hydroxide-copper selenide nanocomplex was prepared by anchoring copper selenide on manganese iron layered double hydroxide nanosheets. This nanocomplex can specifically release CuSe, Mn²⁺ and Fe³⁺ in the tumor microenvironment, which implements NIR-II photoacoustic imaging-guided synergistic cancer therapy under 1064 nm laser irradiation.