Synthesis gas (syngas) is a versatile intermediate in the production of valuable chemicals and fuel, such as methanol, dimethyl ether, ethylene, propylene, and the Fischer–Tropsch fuel. Combining steam reforming and dry reforming (SR + DR) routes can produce syngas with a suitable H2:CO molar ratio (around 2:1) for Fischer–Tropsch synthesis. The newly proposed tri‐reforming (TR) route at experimental scale was a capable alternative to produce syngas in a single reformer with potential benefits such as energy savings and waste flue gas utilization. In this paper, sustainability assessment of SR + DR and TR routes adopting quantifiable indices in economic, environmental, and safety dimensions at industrial scale is performed based on process simulation models. Results show that TR route outperforms SR + DR route in all 3 dimensions. Sensitivity analysis of natural gas price fluctuation does not alter the conclusion. A sustainable root cause analysis is also applied on the SR + DR which identifies root causes affecting its sustainability with the aid of visualization tools such as Pareto chart and fish bone diagram.