Calix[4]arene-segmented polyurethane (CPU) was synthesized in a two-step reaction. The synthesis of CPU was confirmed by measurements of FT-IR and H-1-NMR spectroscopy. The CPU nanocomposites with single-walled carbon nanotubes (SWCNTs) showed non-agglomerated homogeneous dispersion of SWCNTs in the CPU matrix according to field emission scanning electron microscope measurements. The mechanical properties of the CPU were enhanced by incorporation of the SWCNTs due to the nano-reinforcement effect of the SWCNTs and the long-range structure of the polymer. It has been demonstrated that these CPU-SWCNT nanocomposites possess the robust mechanical and thermal behavior.