The compatibilizing effect of styrene-co-4-vinylpyridine (SVP) random copolymers on the immiscible polystyrene (PS)-polyethylene-based ionomer (Surlyn) blends was examined by means of scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and tensile test. For the binary SVP-Surlyn and ternary PS-Surlyn-SVP blends, the domain size of dispersed phase decreases dramatically with the increase in the vinyl pyridine (VP) content of the SVP copolymers. The mechanical properties are improved with increasing the VP content in copolymers. FTIR results suggest that the compatibilization in this blend system is attributed to the ion-dipole interaction between the polar VP groups of SVP copolymer and ionic groups of Surlyn.