Alkali metal doping is a new and promising approach to enhance the photo/electrocatalytic activity of NiS-based catalyst systems. This work investigates the impact of sodium on the structural, electronic, and catalytic properties of NiS. Comprehensive characterization techniques demonstrate that Na-doping causes significant changes in the NiS lattice and surface chemistry translating into a larger bandgap than NiS. Photocatalytic experiments demonstrate 98.5% degradation of 2,4-DCP under visible light, attributing it to improved light absorption and charge separation by Na-NiS nanoparticles. The effect of pH and pKa on the degradation of 2,4-DCP has also been studied and reported. Additionally, electrochemical measurements of Na-NiS indicate overpotentials of 336 mV towards hydrogen evolution reaction (HER) and 350 mV towards oxygen evolution reaction (OER). The material's overall water splitting is found to be 2.61 V at a current density of 10 mA cm-2. The results highlight the potential of Na-NiS as a versatile catalyst for environmental remediation and clean energy applications, paving the way for further exploration and optimization of doped transition metal sulfides.