Efficient and robust electrocatalysts for the hydrogen evolution reaction (HER) are essential to support the transition to clean and sustainable energy systems. Transition metal chalcogenides, particularly those with tunable compositions, have shown great promise due to their intrinsic catalytic activity and cost-effectiveness. In this study, a quaternary NiWSSe electrocatalyst was developed by integrating nickel (Ni), tungsten (W), sulfur (S), and selenium (Se) to enhance HER performance through synergistic electronic effects and optimized active sites. The catalysts were synthesized via a hydrothermal method followed by thermal annealing under a reducing atmosphere. Structural and compositional analyses were performed using XRD, SEM, EDS, and XPS techniques. Electrochemical performance was evaluated in 0.5 M H₂SO₄ using linear sweep voltammetry (LSV), Tafel slope analysis, and electrochemical impedance spectroscopy (EIS). Among the various compositions tested, Ni_0.25W_0.75SSe exhibited the highest catalytic activity, achieving a low overpotential of 137 mV at a current density of 10 mA cm^-2 and a Tafel slope of 43.07 mV dec^-1. The Ni_0.25W_0.75SSe catalyst exhibits a low charge transfer resistance (R_ct) of 40 Ω, as revealed by EIS measurements, indicating enhanced electrical conductivity and faster HER kinetics. The enhanced performance is attributed to W-induced electronic modulation and Se-associated defect sites, which collectively promote efficient charge transport and increase the availability of catalytically active edge sites. Overall, Ni_0.25W_0.75SSe demonstrates excellent HER activity and stability, making it a promising material for scalable hydrogen production applications.