The vast majority of bacteria require iron for growth. Iron is an essential element required for key biological processes including amino acid synthesis, oxygen transport, respiration, nitrogen fixation, methanogenesis, the citric acid cycle, photosynthesis, and DNA biosynthesis. However, obtaining iron presents challenges for the majority of microorganisms. In the ocean, the distribution of iron in the marine environment is spatially heterogeneous, which is one of the main limiting factors affecting marine primary productivity. Dissolved iron is a scarce resource for marine creatures because it is mainly present as a less soluble trivalent state (Fe³⁺), which makes it prone to settling and being “removed”. Marine microorganisms are presented with unique challenges to obtain essential iron ions required to survive and thrive in the ocean. To obtain enough iron source for life metabolism, microorganisms have evolved many ways to meet the demand for iron intake, among which siderophores is the most representative one. Siderophores are low molecular mass iron-binding ligands produced by marine bacteria. Microbial siderophores are multidentate Fe³⁺ chelators used by microbes during siderophore-mediated assimilation. They possess high affinity and selectivity for Fe³⁺. Among them, marine siderophore-mediated microbial iron uptake allows marine microbes to proliferate and survive in the iron-deficient marine environments. Being an important metabolic cofactor, siderophores also strongly influences the circulation of other elements. In order to better understand the role of siderophores in marine microbial ecology and deepen our understanding of marine iron cycle dynamics, this paper summarizes the types of siderophores such as hydroxamates, catecholates and carboxylates, two main siderophores synthesis pathways of microorganism and the mechanism of regulating siderophores synthesis, describes the transmembrane transport process of siderophores and several functional protein elements, the functions of siderophores such as anti-oxidative stress, regulation of pathogen virulence, formation of multifunctional iron and sulfur polymers, and anti-pathogens and so on. Although siderophores have been studied and discussed, further research can be carried out in the following aspects, such as the interaction mechanism between siderophores and marine microorganisms, the application of synthetic biology, and the coupling ability of siderophores behavior with other elements.