This research article focuses on the preparation of chlorinated natural rubber (Cl-NR)/nickel oxide (NiO) nanocomposites by a simple and greener two-roll mill mixing technique. X-ray diffraction study of the rubber nanocomposites showed the systematic arrangement of NiO nanoparticles in the polymer indicates the improved crystallinity of the nanocomposites. The composite prepared with a nanofiller content of 5 phr (parts per hundred parts of rubber) exhibited the best homogenous dispersion of filler in rubber as evident from field emission scanning electron microscopy and HRTEM images. The glass transition temperature obtained from differential scanning calorimetry (DSC) was found to be increased with an increase in the concentration of nanofiller in the polymer. The flame resistance of rubber composites was significantly improved with increasing the filler content and this aids the fabrication of fireresistant household gadgets. The AC conductivity and dielectric behavior of composites were scrutinized with special emphasis on filler loading at various frequencies. The AC conductivity, dielectric loss and dielectric constant of the nanocomposites were higher than pure Cl-NR. The cure time was considerably reduced with the incorporation of filler, resulting in the easy fabrication of rubber products at a cheaper rate. The mechanical properties (tensile strength, modulus, hardness, tear resistance, heat build-up) of the nanocomposites were increased with the addition of NiO indicating its high reinforcing ability. The maximum mechanical and electrical properties were observed for 5phr NiO loaded nanocomposite and these samples can be potential candidates for the fabrication of electromagnetic induction shielding materials, conducting adhesives and flame resistant flexible electronic devices.