Regulating the level of reactive oxygen species (ROS) in a tumor is an efficient and innovative anticancer strategy. However, the therapeutic efficacy of ROS-based therapies, such as chemodynamic therapy (CDT) and photodynamic therapy (PDT), offers finite outcomes due to the oxygen dependence and limited concentration of hydrogen peroxide (H2O2) and overexpression of glutathione (GSH) within the tumor microenvironment (TME), so a single therapeutic strategy is insufficient to completely eliminate tumors. Therefore, we demonstrated an omnipotent nanoplatform MnO2/Ag3SbS3 (abbreviated as MA) with strong optical absorbance in the NIR-II biowindow and oxygen self-sufficient ROS-mediated ability, which not only relieves tumor hypoxia significantly but also enhances the photothermal therapy (PTT)/PDT/CDT efficacy. By 1064 nm laser irradiation, MnO2/Ag3SbS3 nanoparticles (NPs) reveal a favorable photothermal conversion efficiency of 23.15% and achieve a single-laser-triggered NIR-II PTT/PDT effect, resulting in effective tumor elimination. Once internalized into the tumor, MnO2/Ag3SbS3 NPs will be degraded to Mn2+ and Ag3SbS3. The released Ag3SbS3 NPs as a NIR-II phototherapy agent could be utilized for photoacoustic imaging-guided NIR-II PDT/PTT. Mn2+ could be used as a Fenton-like catalyst to continuously catalyze endogenous H2O2 for generating highly virulent hydroxyl radicals (•OH) for CDT and O2 for PDT, enhancing the efficiency of PDT and CDT, respectively. Meanwhile, Mn2+ realizes magnetic resonance imaging-guided accurate tumor therapy. Moreover, the MnO2/Ag3SbS3 NPs could deplete intracellular GSH in TME to promote oxidative stress of the tumor, further strengthening ROS-mediated antitumor treatment efficacy. Overall, this work presents a distinctive paradigm of TME-responsive PDT/CDT/PTT in the second near-infrared biowindow by depleting GSH and decomposing H2O2 for efficient and precise cancer treatment.