A novel procedure for the synthesis of polyarylethenes is described. Consecutive C–H vinylation reactions of tetraphenylethene with a triphenylethenyl triazene give hyperbranched polyarylethenes of variable sizes. The vinylation reactions are mediated by acid-induced cleavage of the triazene function. In contrast to other procedures for the synthesis of polyarylethenes, our methodology is ‘traceless’, and functional groups are not found in the products. The hyperbranched polyarylethenes show size-dependent luminescence. Larger polymers display increased luminescence in solution but decreased luminescence in the solid state. The polymers exhibit unusual ratiometric aggregation-induced emission. The synthetic methodology can also be used for grafting hyperbranched poly(triphenylethene) to a functional aromatic compound such as benzo-18-crown-6. The coupling product displays a ratiometric luminescence response upon the addition of metal salts.