Antibiotic-resistant bacterial strains have become an ever-increasing public concern due to their significant threats to health safety. Nanomaterial-based photothermal treatment has shown potential in antibacterial applications, but many nanomaterials exhibited limited photothermal activity that may compromise their antibacterial efficacies. Herein, we report a novel strategy based on efficient photothermal ablation and physical contact over a supported nanostructure by loading Au nanoparticles (NPs) on few-layered Ti3C2Tx nanosheets (NSs) for antibacterial treatment. Ti3C2Tx NSs are delaminated via etching and sonication, and act as a reductant for the in situ reduction of HAuCl4·xH2O, producing "naked" Au NPs without any stabilizers. Meanwhile, by adjusting the Au/Ti ratio, the size and loading of the Au NPs are finely regulated, thereby providing an ideal model of a surface-clean Au@Ti3C2Tx heterostructure for probing the composition-performance relationship. Upon irradiation with visible light, it exhibits synergistically enhanced photothermal conversion efficiency and stability, owing to the localized surface plasmonic resonance effect of Au NP and Au-NS interactions. Moreover, under visible light irradiation for 10 min, the Au@ Ti3C2Tx heterostructure exhibits excellent antibacterial activity for Gram-positive S. aureus and Gram-negative E. coli, and kills over 99% bacteria with a low dose of the nanomedicine suspension (50 μg mL-1). The work demonstrates that the incorporation of transition metal carbides with plasmonic metal nanostructures is an effective strategy to enhance the photothermal antibacterial efficacy.