The rapidly increasing global energy demand, coupled with the urgent need for sustainable and clean energy carriers, has positioned hydrogen as one of the most promising alternatives to fossil fuels. Hydrogen offers several advantages, including a high gravimetric energy density and zero-carbon emissions at the point of use, making it highly attractive for future energy systems. Among the various hydrogen production routes, water electrolysis is particularly appealing because it directly generates high-purity hydrogen. However, the large-scale of this technology relies heavily on the development of efficient and durable electrocatalysts that are both cost-effective and derived from earth-abundant elements, thereby eliminating dependence on scarce and expensive noble metals. In the present work, we report the successful synthesis of a quaternary NiFeSSe electrocatalyst using a hydrothermal method. Different compositional ratios were systematically explored, and the Ni_0.25Fe_0.75SSe composition was identified as the most effective for the hydrogen evolution reaction (HER) in acidic media. Specifically, in 0.5 M H₂SO₄, Ni_0.25Fe_0.75SSe demonstrated a low overpotential of 158 mV at a current density of 10 mA cm^-2, with a corresponding Tafel slope of 101.02 mV dec^-1, highlighting its favorable HER kinetics. Moreover, it maintained relatively low overpotentials at higher current densities of 50 and 100 mA cm^-2, respectively. Long-term durability tests confirmed its robust stability, as only a slight increase in overpotential after 1000 linear sweep voltammetry cycles. The enhanced electrocatalytic activity of Ni_0.25Fe_0.75SSe can be attributed to the synergistic interactions between Ni and Fe, which modulate the electronic structure and facilitate the Volmer-Heyrovsky reaction pathway for hydrogen evolution. This study demonstrates that Ni_0.25Fe_0.75SSe is a promising, noble-metal-free electrocatalyst that offers a cost-effective and stable alternative to Pt-based systems, advancing the prospects of sustainable hydrogen production.