PET and PMMA were blended at various weight fractions. These blends were compatibilized by employing amphiphilic block copolymers of PtBA-b-PMMA, having three compositions (1:3, 1:1, 3:1) and three weight fractions (3, 5, and 7 wt%) using a co-rotating twin screw extruder. The blends were evaluated for their mechanical, Theological, and morphological properties. Overall, the compatiblized blends showed improvement in properties compared with the properties of noncompatiblized blends. Mechanical properties of the compatibilized blends improved with an increase in the PMMA and compatibilizer weight fractions. It was observed that the compatibilizer with lower molecular weight and lower glass transition temperature, typically at 5 wt%, provided the overall best properties.