Miscibilities of segmented polyurethanes (SPUs) and poly(vinyl chloride) (PVC) or functionalized poly(vinyl chloride) (FPVC) were studied with dynamic mechanical analysis, differential scanning calorimetry, and X-ray diffraction. Mechanical properties of the blends were also studied with tensile measurements. The miscibility of the blends depended greatly on the hard-segment content of SPU and the existence of the functional groups. The combination of SPU with a low hard-segment content and PVC with functional groups made the blend system miscible. Moreover, controlling the blend composition of SPU/FPVC allowed us to modify the mechanical properties of SPU, where the elongation at break was multiplied without a significant change in its tensile strength.