This study introduces a novel and integrated configuration aimed at the complete and maximum utilization of waste heat in order to enhance exergy efficiency. In the proposed system, which is capable of simultaneous power and hydrogen production, a high-temperature supercritical carbon dioxide (sCO2) cycle is directly integrated with a lower-temperature Rankine cycle. The primary innovation of this system lies in its advanced internal heat management structure, whereby the heat rejection process of the sCO2 cycle is replaced by the evaporation process in the Rankine cycle. This approach enables effective recovery of internal heat and its conversion into additional power output. A portion of the net power generated by this high-efficiency thermodynamic system is fully allocated to a proton exchange membrane (PEM) electrolyzer for green hydrogen production. To comprehensively evaluate the thermodynamic performance and economic potential of the system, detailed exergy and exergoeconomic analyses are conducted. The results demonstrate that the proposed integrated configuration significantly reduces total exergy destruction while achieving a substantial increase in power output and elevating the hydrogen production rate to optimal levels. Overall, this cogeneration system is presented as an efficient and effective solution for clean energy production from low-grade thermal resources.