This study evaluates a new standalone polygeneration system designed to convert waste-heat steam into electricity, green hydrogen, freshwater, and cooling via an integrated Organic Rankine Cycle (ORC), Proton Exchange Membrane (PEM) electrolyzer, Humidification–Dehumidification (HDH) desalination unit, and Adsorption Cooling System (ACS). The thermodynamic performance of the integrated system is modeled and analyzed under varying waste steam qualities (0.05–0.97) and heat allocation ratios using MATLAB® simulations. Results indicate that increasing the inlet steam quality from 0.05 to 0.97 linearly scales the ORC net power output from 72.65 kW to 929.66 kW, driving the PEM electrolyzer to produce hydrogen at rates ranging from 1.79 kg/h to 20.70 kg/h, respectively. The residual heat is recovered to drive the bottoming cycles; an optimal allocation strategy (95% heat to HDH at 7 kg/s saline flow) achieved a peak freshwater yield of 901.2 kg/h (GOR = 1.12). Conversely, balanced configurations (20% HDH / 80% ACS) maximized the bottoming cycle synergy, delivering 17.98 kW of cooling (COP = 0.506). A critical thermodynamic trade-off is observed regarding the overall Energy Utilization Factor (EUF); while high steam qualities maximize hydrogen yield, the EUF declines to approximately 4.4% due to high latent heat consumption. However, optimizing the configuration for low-quality steam (Configuration 9) achieved a peak EUF of 46.87% by maximizing freshwater recovery. The study concludes that adaptive heat allocation is essential to balance the trade-off between high-value hydrogen production and overall thermal energy utilization.