In this present work, a simple electroless deposition method is used for the fabrication of hexacyanoferrate(III)-nickel deposited pencil graphite (HCF-Ni-PGE) electrode and applied as an electrochemical sensor for selective and simultaneous determination ofortho-I andpara- nitrophenol II isomers. The fabricated HCF-Ni-PGE was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and elemental mapping. The electrochemical analysis was carried out using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques in 0.1 M KCl containing K-4[Fe(CN)(6)]. The redox (Fe2+/3+) peak currents were enormously increased due to the successful enhancement in the electroactive surface area of PGE from 0.4 to 1.57 cm(2)for HCF-Ni-PGE. Further, CV and EIS support the HCF and Ni coating on the PGE surface enhanced the electronic conductivity of HCF-Ni-PGE. The electrochemical sensor application of HCF-Ni-PGE was analysed using CV and differential pulse voltammetry towards the determination ofo- andp-NP in 0.1 M PBS (pH 6.0). The reduction currents of I and II at HCF-Ni-PGE was enhanced two times compared with the PGE with better resolution. This, the enhanced activity is due to the positive synergetic effect which increased an electroactive surface area, and electronic conductivity. The limit of detection (LOD) values at HCF-Ni-PGE for I and II isomers are 1.98 x 10(-7)and 1.43 x 10(-7)M with S/N = 3, respectively. The practical applicability of the electrochemical sensor has been investigated in the presence of common interfering agents such as Na+, SO(4)(2-)and phenol. The simple electroless deposition used for the fabrication of HCF-Ni-PGE electrode possessed high surface area and high conductivity, it can also be applicable in the field of energy storage devices of supercapacitor, and battery, fuel cells and solar cells as electrode materials and photocatalysts.