One of the main challenges in the reduction of the electromagnetic wave is to develop lightweight absorber material with a wide absorption frequency. Hence, developing shielding materials that could shield electromagnetic radiation to prevent interference is highly desired for protection. The combination between the unique properties of polyamide (PA6) with free surfactant magnetite nanoparticle as core/shell nanofibers (PA6 @ Fe3O4) provides a promising low-cost, environmentally-friendly and electromagnetic shielding properties. Free surfactant magnetite nanoparticles (39 +/- 3.5 nm average size) were prepared by the co-precipitation process and incorporated directly into the polyamide solution before the electrospinning technique. The mean average size of the prepared magnetite nanoparticles is compared based on X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM). The morphology, thermal stability and magnetic behavior of the resultant magnetite nanofibers (150 +/- 25 nm average size) were investigated using high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA) and vibrating sample magnetometer (VSM), respectively. Shielding effectiveness for magnetite polyamide core/shell nanofibers was measured at frequency 30 MHz-1.5 GHz. The results showed that core/shell nanofibers provide not only well-dispersed magnetite nanoparticles in the polyamide matrix but also controllable sized nanofibers with high magnetization. In addition, even with low magnetite loading of 1.7%, the fabricated nanofiber shows high thermal stability with good performance as electromagnetic shielding nanofiber. Therefore, magnetite polyamide core/shell nanofiber could be considered as a promising material for shielding application.