Light alkanes are natural organic carbon sources and widely distributed in nature. Transforming them into value-added fine chemicals affords attractively economic and ecological benefits as well as enormous chemical challenges. Herein, we report a practical iron-catalysed photoredox system for C(sp³)–H transformation of ethane, propane, and other light alkanes to C–N and C–C bonds under ambient temperature. The present method with abundant and inexpensive iron salts as photocatalysts exhibits high catalytic efficiency (turnover number up to 8000), mild conditions, and the convenience of being purified and scaled up without chromatography. A photo-induced ligand-to-metal charge transfer between Fe(III) and Cl⁻ generates a highly active chlorine radical that sequentially acts as hydrogen atom transfer catalyst. Therefore, the sustainable, convenient, and environmentally friendly system will find wide applications in high-value-added transformation of natural alkanes with novel inspiration not only for organic synthesis, but also for designing catalytically active organic/inorganic materials.