A simple compounding technique for the fabrication of polymer nanocomposites with single-walled carbon nanotubes having exceptional alignment and improved mechanical properties is described. The aligned-nanotube composite was prepared by dissolving single-walled carbon nanotubes in a solution of thermoplastic polyurethane and tetrahydrofuran. Solvent-polymer interactions that induce the orientation of soft chain segments during the swelling and moisture curing stage are believed to serve as a driving force for the macroscopic alignment of the carbon nanotubes.