<p>This study presents a techno-economic and environmental assessment of hydrogen integrated hybrid renewable energy systems for an off-grid eco-industrial park (EIP) in Batman, Turkey. An EIP is an industrial area where energy, water, and resource flows are optimized to minimize environmental impact and enhance efficiency through renewable integration and circular resource management. Three alternative configurations were evaluated using the HOMER Pro platform: high-renewable (Scenario 1), diesel-assisted (Scenario 2), and grid-connected (Scenario 3). The life span of the proposed hybrid energy system is considered as 25&#xa0;years for the techno-economic analysis. Scenario 1 achieved an optimized balance with a net present cost (NPC) of $50.2&#xa0;M, levelized cost of energy (LCOE) of 0.274&#xa0;$ kWh^-1, and a 67% renewable fraction, with generation shares of PV 50.9%, biogas 24.9%, wind 19.3%, and fuel cell 4.9%. Scenario 2, with a renewable share limited to 38.4%, yielded a slightly lower LCOE (0.270&#xa0;$ kWh^-1) but a higher NPC ($53.9&#xa0;M) due to fuel and operational expenses. Although the grid-connected Scenario 3 showed the lowest LCOE (0.129&#xa0;$ kWh^-1), its renewable contribution remained 30.8%, and CO₂ emissions increased sharply because of fossil-based grid dependency. The environmental impact of the scenarios was evaluated using HOMER Pro’s built-in emission factor-based methodology. Thermal analysis revealed that the biogas–CHP configuration in Scenario 1 met nearly half of the annual heating demand, reducing boiler use and achieving a 50% CO₂ reduction compared to the diesel-based configuration and 68% compared to the grid-connected system. Overall, the PV–wind–biogas–hydrogen hybrid system demonstrated the most balanced performance in cost, reliability, and sustainability, providing a feasible pathway toward low-carbon and energy-secure eco-industrial parks in similar climatic regions.</p>