As a key active component of the black carbon continuum, Dissolved Black Carbon (DBC) exhibits markedly distinct molecular structural characteristics and environmental fate attributes compared with particulate black carbon. Originating from the incomplete combustion of biomass and fossil fuels, DBC is highly reactive and mobile, with colloidal particles facilitating its transport approximately three times faster than that of particulate black carbon. This enables extensive participation in biogeochemical cycles through interfacial complexation, redox regulation, and biological metabolism. These processes are integral to the Earth’s material cycles and energy transformations. This study systematically analyzed the structural heterogeneity of DBC derived from various sources, emphasizing its environmental behavior, such as aggregation influenced by cation valency and salinity, adsorption onto mineral surfaces, redox-mediated transformation of heavy metals, and photochemical reactions across soil-water-atmosphere interfaces. We further elucidated how DBC profoundly influences ecosystem structure and function by regulating elemental cycles (e.g., enhancing carbon sequestration and promoting nitrate reduction), mediating iron mineral transformation, facilitating contaminant transport and transformation, and exerting dual effects on microbial and plant metabolism. Its complex role is evident as it can serve as a nutrient source yet also induce oxidative stress or enhance heavy metal uptake in crops. However, current understanding is constrained by technical limitations in resolving molecular fingerprint isomers, quantifying interfacial reaction kinetics in situ, and dynamically characterizing micro interfacial processes. Overcoming these bottlenecks is essential to unravel the evolutionary mechanisms, interface dynamics, and ecological risks of DBC-pollutant/element coupling systems. This review synthesizes the current knowledge and aims to provide a theoretical foundation for accurately assessing the ecological and environmental impacts of black carbon cycling in the context of global change. This further highlights the need for advanced predictive models and in-situ techniques to support ecological conservation, pollution control, and sustainable environmental management.