The rheological behavior of multilayered reactive polymers was investigated. Dynamic mechanical experiments were performed to probe the effect of the interfacial area on the rheological behavior of a multilayered structure as compared to that of a droplet-type morphology. Polyamide (PA6)/polyethylene grafted with glycidyl methacrylate was used as a model system, and in the molten state, such a system generated a reaction between amine, carboxylic, and epoxy groups. Multilayer structures containing various amounts of both interfacial area and volume fractions of the two components were studied. Relationships between viscoelastic material functions and compositions were used to analyze the effects of bulk and reactive functions in the polyolefin phase at the interface with PA. The contribution of the interface/interphase effect was investigated along with the increase in the number of layers, and the results showed that the variation in dynamic modulus of the multilayer system was a result of both diffusion and chemical reaction. Specific experiments were carried out to separate the thermodynamic effects from the kinetic ones, and the results were rationalized by comparing the obtained data with theoretical models. Finally, the effect of the interface/ interphase triggered between the neighboring layers was quantified at a specific welding time and shear rate.