A series of new homopolymers with various degrees of polymerization derived from vinyl tetraphenylethene, that is, poly[2-(4-vinylphenyl)ethene-1,1,2-triyl)tribenzene] homopolymers, is synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. The homopolymers exhibit a significant aggregation-induced emission (AIE) effect and an ability to assemble themselves into AIE polymer nanoparticles (NPs) during precipitation in a water/tetrahydrofuran (THF) mixture. The NPs also exhibit good dispersibility, stability, and biocompatibility. The AIE polymer NPs are used in imaging studies of HeLa cells.