One of the most important issues of today and the near future is access to clean and sustainable energy and fresh water. To meet current energy demands, we are still widely using carbon-based fuels, which are the main contributors to environmental problems. In this developed study, a comprehensive thermodynamic performance modeling is executed for power, fresh water, and hot water generation with energetic and exergetic efficiency approaches. The newly configured plant comprises a double-flash geothermal power plant, a reverse osmosis (RO) desalination unit, a multistage flash desalination (MSFD) process, and a hot water preparation unit. To ascertain the performance of the developed model, simulations of energy efficiency, exergy efficiency, and exergy destruction are conducted for each component and the entire system. In addition, parametric investigation is executed to define the effect of the significant indicators on the system’s efficiency. Finally, the developed plant is also examined by the sustainability index (SI) evaluation. The consequences display that the developed plant has a 15.45% energy efficiency, and a 23.55% exergy efficiency, and the power generation load is computed as 957.6 kW.