Fluorescent silica nanoparticles (FSNPs) with efficient light emission, colloidal stability, and size tunability are fabricated by one-pot, two-step Stöber and reverse microemulsion techniques. Tetraphenylethene (TPE)- and silole-functionalized siloxanes are facilely synthesized by click reactions and their sol–gel reactions followed by reactions with tetraethoxysilane generate FSNPs with core–shell structures. The FSNPs are uniformly sized with smooth surfaces, and show high surface charges and hence excellent colloidal stability. UV irradiation of ethanol solutions of the FSNPs gives strong blue and green light at 474 and 486 nm in high fluorescence quantum yields, thanks to the novel aggregation-induced emission attributes of the TPE and silole aggregates in the hybrid nanoparticles. The FSNPs are benign to living cells and function as fluorescent visualizers for intracellular imaging of HeLa cells.