Gold nanoparticles (Au NPs) used as photosensitizers for photothermal therapy (PTT) have attracted extensive attention. However, limited tissue penetration of light seriously hinders the practical application, causing Au NPs to be combined with multiple theranostic agents to improve the treatment effect. Herein, we fabricate one potent gold nanostars (GNS) that can unify the dual nanozyme activities and photothermal property, achieving effective synergistic cascade catalytic and photothermal therapy. Notably, GNS is prepared by a green and facile one-step synthesis method using biodegradable poly(γ-glutamic acid) as a medium. The single GNS exhibits inherent dual nanozyme activities, glucose oxidase- and peroxidase-like activities, which not only convert glucose of tumor tissue into hydrogen peroxide (H2O2) but also catalyze H2O2 to produce the amount of toxic hydroxyl radicals (•OH), leading to an amplified cascade catalytic therapy. Moreover, the cascade catalytic activity of GNS is enhanced 1.4-fold in the photothermal effect. Finally, the GNS can achieve photoacoustic imaging-guided efficient synergistic cascade catalytic and photothermal therapy with a high antitumor rate of 97.0%. This simple but multifunctional GNS could provide a new strategy facilitating the practical treatment application of single Au NPs.