In nature, nitrogen fixation is one of the most important life processes and occurs primarily in microbial organisms containing enzymes called nitrogenases. These complex proteins contain two distinct subunits with different active sites, with the primary N2 binding site being a FeMoS core cluster that can be reduced by other nearby iron-sulfur clusters. Although nitrogen reduction to ammonia in biology does not require the absorption of light, there is considerable interest in developing catalyst materials that could drive the formation of ammonia from nitrogen photochemically. Here we report that chalcogels containing inorganic FeMoS clusters are capable of photochemically reducing N2 to NH3 under white light irradiation, in aqueous media, under ambient pressure and at room temperature. The chalcogels are composed of [Mo2Fe6S8(SPh)3]3+ and [Sn2S6]4- clusters in solution and have strong optical absorption, high surface area, and good aqueous stability. Our results demonstrate that light-driven nitrogen conversion to ammonia by MoFe sulfides is a viable process with implications in solar energy utilization and our understanding of primordial processes on earth.