Recently, studies on ionizing radiation application on thermoplastic nanocomposites have increased due to benefits of carbon nanofillers affecting increase of mechanical properties, reduction of oxidation effects and improvement of thermal properties. However, the thermomechanical and dielectric properties are less studied. In this work, ethylene-octene copolymer (EOC, 1-octene content 17 wt.%) with BayerTM multi-walled carbon nanotubes (CNT content 0-15 wt.%) was irradiated with accelerated electrons up to 150 and 300 kGy absorbed doses. The studies by dynamic mechanical analysis and tensile tests at 25 and 50oC temperatures indicated increase of tensile strength and elastic modulus with the rise of filler content and irradiation dose. It was determined that radiation cross-linked EOC/CNT compositions remained high deformability at CNT content up 5 wt.% (elongation at break 100-200%) suitable for obtaining thermo-shrinkable materials with by 35% higher heat-relaxation forces than that of pristine EOC at 150 kGy absorbed irradiation dose. The value of conductivity for irradiated EOC/CNT compositions increased by 7 to 40 times at the filler contents reaching 5-15 wt.%, compared to unirradiated blends.