This review integrates vent fluid chemistry and biogeochemical processes to assess how hydrothermal systems influence oceanic iron distribution. Despite rapid precipitation of iron-bearing minerals immediately after venting, buoyant hydrothermal plumes disperse dissolved and nanoparticulate iron across thousands of kilometers, aided by slow oxidation, reversible exchanges between soluble and particulate iron, and biological interactions. These mechanisms underscore hydrothermal vents as a widespread iron source, impacting deep and surface marine ecosystems. Transport dynamics are governed by temperature, pH, microbial activity, and water-mass residence times. We investigate the controls on hydrothermal iron distribution by examining relationships between iron and pH, temperature, chlorinity and hydrogen sulfide in vent fluids, along with solubility modeling of iron(III) hydroxide and iron(II) sulfide. Finally, we highlight key research frontiers that will advance understanding of both hydrothermal processes and their role in shaping the ocean iron biogeochemical cycle.