The formation of amylose−polystyrene inclusion complexes via a novel two-step approach is described. In the first-step, styrene was inserted inside the amylose helical cavity, followed by free radical polymerization in the second step. The inclusion complexes were characterized by attenuated total reflection fourier transform infrared spectroscopy (ATR-FTIR), ultraviolet spectroscopy (UV), X-ray diffraction (XRD), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). The formation of polystyrene was confirmed by gel permeation chromatography (GPC). The molecular weight of polystyrene can be varied by using amylose bearing different molar masses. The approach described here is general and could be used to synthesize other host−polymer inclusion complexes for which long chains of polymeric guests are difficult to insert into the host cavity.