Both the variety and uniqueness of organic semiconductors has contributed to the rapid development of environmental engineering applications and renewable fuel production, typified by photo-degradation of organic pollutants or water splitting. This paper presents a rare example of an aggregation-induced emission luminogen (AIEgen) as a highly efficient photo-catalyst for pollutant decomposition in an environmentally relevant application. Under irradiation, the tetraphenylethene-based AIEgen (TPE-Ca) exhibited high photo-degradation efficiency of up to 98.7% of Rhodaminein (RhB) in aqueous solution. The possible photocatalytic mechanism was studied by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) spectra, electrochemistry, thermal imaging technology, ultra-performance liquid chromatography and high-definition mass spectrometry (UPLC/HDMS), as well as by density functional theory (DFT) calculations. Cytotoxicity experiments indicated that the final photo-catalytic degradation products show biocompatibility. Among the many diverse AIEgens, this is the first AIEgen to be developed as a photo-catalyster of organic pollutants. This research will open up new avenues for AIEgens research, particularly for applications of environmental relevance.