Despite the immense potential of photodynamic therapy (PDT) in cancer treatment, its clinical translation remains constrained by nonspecific photosensitizer activation and limited therapeutic efficacy. Herein, we design glutathione (GSH)-responsive organic–inorganic hybrid nanoprobes (AuPPCs) featuring a dual-quenching mechanism for tumor-specific multimodal theranostics. AuPPCs utilize gold nanorods (AuNRs) as multifunctional photothermal transducers, photosensitizer quenchers, and photoacoustic signal reporters, which are modified with copper-chelated diethylenetriaminepentaacetic acid (Cu-DTPA) and pyropheophorbide-a (PPa) photosensitizers via GSH-cleavable linkers. Such a design makes the PDT efficacy of PPa quenched simultaneously by Cu-DTPA and AuNRs. The activation of AuPPCs is achieved through tumor overexpressed GSH, which can trigger disulfide cleavage to release PPa. Compared with Cu-DTPA-conjugated PPa (Cu-PPa), AuPPCs show enhanced photodynamic efficacy and fluorescence signals upon activation of GSH. On the other hand, GSH may induce Cu2+ reduction to generate Cu+, enabling the Fenton-like catalytic conversion of endogenous H2O2 to hydroxyl radicals (˙OH) for chemodynamic therapy (CDT). The photothermal effect of AuNRs synergistically enables photothermal therapy (PTT) and real-time photoacoustic imaging of the tumor. This triple-modality integration (PTT/PDT/CDT) achieves 83.16% tumor suppression with negligible systemic toxicity, outperforming individual therapeutic modalities. Thus, this work reports a high tumor-specific nanotheranostic platform with dual-quenched PDT efficacy for imaging-guided combination therapy.