Energy security is a critical prerequisite for sustainable economic and industrial development. In Iran, it is of particular importance due to the dominant role of natural gas in the national energy mix. This study examines the structure of energy consumption, analyzes the natural gas supply–demand imbalance, and evaluates its implications for energy security and the competitiveness of energy-intensive industries. The research adopts an applied descriptive–analytical approach and utilizes data obtained from Iran’s Energy Balance Sheets, reports of the Ministry of Petroleum, the Ministry of Energy, the National Iranian Gas Company, the Iranian Parliament Research Center, the International Energy Agency (IEA), and the financial statements of publicly listed companies. The findings reveal that the extensive dependence of the residential, power generation, and industrial sectors on natural gas, together with rapid demand growth, investment constraints, infrastructure limitations, and high energy intensity, has significantly exacerbated the gas supply–demand imbalance and increased vulnerabilities in the country’s energy security. The analysis further indicates that energy-intensive industries, particularly the petrochemical, steel, and cement industries particularly the petrochemical, steel, and cement industries, are highly exposed to gas supply disruptions. Such constraints result in production losses, reduced export performance, higher operating costs, and an erosion of competitive advantages in both domestic and international markets. The study also identifies several policy measures for mitigating the imbalance, including reforming the natural gas pricing system, improving energy efficiency, expanding the deployment of renewable energy, encouraging industrial participation in upstream gas field development, and implementing effective demand-side management programs. The study concludes that the Natural Gas Supply–Demand Imbalance in Iran is not merely an energy-sector concern but a strategic challenge with far-reaching consequences for industrial development, economic growth, and long-term energy resilience.