Iron sulfide (Fe-S) minerals such as mackinawite (FeS), greigite (Fe3S4) and pyrite (FeS2) are widespread on Earth, where their formation and dissolution are strongly linked to the biogeochemical cycles of iron, sulfur, carbon, oxygen, nutrients and trace metals. Recent studies have shed light on how microorganisms mediate their formation, with breakthroughs linked to biogenic pyrite. In this review, we highlight the formation pathways of Fe-S minerals, starting with the increasingly recognized roles of Fe(III) and intermediate sulfur species (e.g. S0 and polysulfides) during the initial steps. The mechanisms by which microorganisms affect Fe-S mineral formation are compiled and discussed for low (25–35°C) and high (≥ 80°C) temperatures, with specific examples from experimental studies. The morphology and precipitation rates obtained from experiments are compared to natural environments, and their similarities and differences are critically discussed. We then review the current state of the art for Fe-S minerals in the context of the origin of life and as environmental proxies and biosignatures in the geological record using their texture and chemical and isotopic compositions. We end by highlighting the importance of Fe-S minerals for current societal issues, such as the sequestration of organic carbon, the formation of acid drainages, metal recovery and nitrate removal, and their potential use as technological bio-materials in the future.