The present study introduces a novel tri-generation system that is highly efficient and cost-effective, employing a supercritical CO2 (sCO2) Brayton cycle as the primary mover and harnessing the cooling potential from liquefied natural gas (LNG) as a heat sink. This innovative system simultaneously provides electricity, cooling, and hydrogen. By capitalizing on the substantial temperature difference between the high-temperature sCO2 power cycle and the low-temperature LNG cold source, an integrated combination of the Kalina cycle (KC) and organic Rankine cycle (ORC) is utilized. Additionally, the system incorporates a proton exchange membrane electrolyzer (PEME) and an absorption refrigeration cycle (ARC) to create a highly efficient trigeneration system. The system is rigorously evaluated through energy, exergy, and exergoeconomic analyses, which are critical for assessing performance. Additionally, this study conducts a parametric investigation to elucidate the impact of key parameters on system performance. Furthermore, optimization is performed using a genetic algorithm (GA), with the objective of maximizing energy and exergy efficiencies or minimizing the overall product cost. Results from the baseline scenario demonstrate impressive energy and exergy efficiencies of 54.38 % and 59.46 % respectively, along with a low total product unit cost of 11.642 ($/GJ), outperforming existing benchmarks in the literature. The system also provides substantial net power output, cooling capacity, and hydrogen production rates of 276.71 MW, 60.19 MW, and 176.25 kg/h, respectively. This combination of high performance and cost-effectiveness makes the proposed system a versatile choice, underscoring its significance in sustainable and environmentally friendly energy solutions.