Natural gas–hydrogen blending projects commonly encounter economic challenges during implementation, including difficulties in calculating energy?use costs and setting natural gas prices. The absence of a pricing mechanism for hydrogen?blended natural gas has hindered its large?scale deployment and commercial application. This paper, based on the principle of constant unit energy?use cost, integrates factors such as changes in energy efficiency, carbon emissions, and pollutant costs to develop a pricing model for hydrogen?blended natural gas. Building on this model, a series of hydrogen?blending combustion tests were conducted on various types of gas?fired equipment, yielding hydrogen?blending efficiency correction coefficients under different scenarios and establishing a comprehensive hydrogen?blending combustion test database. Under diverse natural gas–hydrogen blending configurations, and leveraging these correction coefficients, a pricing framework for hydrogen?blended natural gas is formulated, providing a reliable valuation tool to support the future promotion and commercialization of such projects.