A single-component multi-modal theranostic platform taking advantage of multiple imaging and therapy techniques may offer improved diagnostic monitoring capabilities and therapeutic efficacies. In this study, through structural tuning, a novel theranostic agent TSSAM with aggregation-induced emission (AIE) characteristics, bright second near-infrared (NIR-II) emission, high reactive oxygen species (ROS) generation capability and excellent photothermal conversion efficiency (40.1%) was developed. TSSAM makes the best use of its excited state energy and keeps perfect equilibrium between radiative and non-radiative transition to satisfy the needs of both NIR-II fluorescence imaging (FLI)/photoacoustic imaging (PAI)/photothermal imaging (PTI) trimodal imaging and photodynamic therapy (PDT)/photothermal therapy (PTT) synergistic therapy. Further experiments validated the superior imaging quality and tumoricidal activity of TSSAM, in which tumor tissues were completely eradicated and tumor metastasis was effectively inhibited by merely single injection and one-time laser irradiation. This research has therefore presented a smart multifunctional material holding great promise in both basic research and clinical practice.