We synthesized novel tetraphenylethene (TPE) conjugates, which undergo unique self-assembly to form spherical nanoparticles that exhibited aggregation induced emission (AIE) in the near-infrared region. These nanoparticles showed significant singlet oxygen generation efficiency, negligible dark toxicity, rapid cellular uptake, efficient localization in cytoplasm, and high in vitro photocytotoxicity as well as in vivo photodynamic activity against a human prostate tumor animal model. This study demonstrates, for the first time, the power of the self-assembled AIE active tetraphenylethene conjugates in aqueous media as a nanoplatform for future therapeutic applications.