The photooxygenation of amyloid-β (Aβ) protein is considered a promising strategy against Alzheimer's disease (AD). The inhibition of Aβ aggregation or depolymerization of Aβ aggregates can effectively alleviate and improve the condition of AD. Herein, we report a series of "off-on" near-infrared quinolinium photosensitizers (QM20-QM22) based on D-π-A structures using a target-sensing catalyst activation (TaSCAc) strategy. They exhibit turn-on fluorescence when bonded to Aβ aggregates and generate singlet oxygen to achieve the specific imaging and photooxygenation of Aβ aggregates, leading to attenuated Aβ aggregates, enhancing their clearance through the microglial lysosomal pathway, decreasing their neurotoxicity. This study will shed light on the development of the photooxygenation of misfolded proteins for the treatment of neurodegenerative diseases.