Around the world, the rubber industry uses 50% of primarily petroleum-based materials with the exception of natural rubber. The use of these petroleum-based raw materials results in increased environmental hazards in addition to the depletion of natural resources. The issue of ground rubber (waste tire rubber) is enormous and has broad environmental and financial ramifications. There are several methods for recycling rubber, including devulcanization, grinding, surface treatment, and reclamation technology. This study aims to investigate the effect of ground rubber (GR) and their concentration on the rheological, morphological, mechanical, physical, and electrical properties of NBR composites. The impact of the chemical treatment ground rubber (GR) on the desired properties is also investigated. The investigated samples are prepared by using two roll mill mixer followed by compression molding at 162 °C. The SEM observations indicate some incompatibility and inhomogeneity in the blends, due to low interfacial adhesion between NBR and GR. However, by replacing GR by modified m-GR particles a more homogenous structure and uniform particle dispersion found, due to improved physical/interfacial interactions. The results also show that the rheological parameters, tensile strength and elongation at break are affected by the treatment of m-GR. The values of permittivity ε' improved after GR modification. Besides, the NBR composites containing m-GR have a promising insulating performance and can be used in electric insulation requirements. Additionally, the values of conductivity of the NBR/ GR and NBR/ m-GR composites are close to ~10-6 S cm–1 at higher GR loading. This value is sufficient for these composites to exhibit electrostatic dissipation behavior.