 This article reports the use of crystalline nickel phosphate/carbon fibres (NiPh/CFs) nanocomposite as an electrode material for pseudocapacitor applications. The NiPh particles are synthesised by a cost-effective one-pot method, which is based on refluxing nickel and phosphate precursors at 90 °C. The crystallinity and structural morphologies of the synthesised particles are characterised by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). Also, the N2 adsorption/desorption isotherms are recorded. The Brunauer–Emmett–Teller (BET) method is used to calculate the specific surface area. The electrochemical performances of pristine NiPh and NiPh/CFs composite electrodes are investigated in an alkaline solution of 0.5 M of KOH. The specific capacitances were calculated using cyclic voltammograms at a potential scan rate of 100 mV s− 1. For the pristine electrode, the calculated specific capacitance was 4.3 F g− 1 and for the composite NiPh/CFs electrode, it was 699.2 F g− 1. The significant improvement in the performance is attributed to the high surface area and enhanced electronic conductivity of the NiPh/CFs composite electrode. Also, the composite electrode shows outstanding stability and delivers 1000 cycles with excellent capacitance retention.