The principles of the creation of new blend polyolefin elastomers with a controlled complex of properties based on a stereoblock elastomeric PP synthesized in the presence of asymmetric ansa-metallocenes are proposed. Original blend polymer materials with reduced hardness that are based on elastomeric PPs with different characteristics and a 50–70 wt % oil-extended ternary ethylene-propylene-diene elastomer were prepared through the method of dynamic vulcanization. The molecular-mass characteristics of PP have a considerable effect on the rheological properties of polyolefin elastomers. For successful processing of the resulting blends, the pristine component, the elastomeric PP, must have a weight-average molecular mass of M w = (8−14) × 104 and a low crystallinity.