Dimanganese decacarbonyl (Mn₂(CO)₁₀) is used as a versatile and efficient visible-light photoinitiator for multiple polymerization techniques in different continuous-flow processes. The use of Mn₂(CO)₁₀ results in efficient photoinitiation of the radical polymerization of methyl acrylate, while its ability to initiate methyl methacrylate polymerization is also demonstrated, as well as the cationic polymerisation of isobutyl vinyl ether (IBVE). In addition, the combination of Mn₂(CO)₁₀ with certain Cu(II) catalysts affords controlled radical polymerization, yielding well-defined polymers with tuneable molecular weights under mild conditions. Polymerizations were performed under blue-light irradiation (λ = 405 nm) in a Corning Advanced-Flow™ reactor (CAFR). Copper mediated protocols were also carried out in a Vapourtec flow reactor coupled with inline benchtop 80 MHz 1H NMR allowing for real-time reaction monitoring. Inline and offline analyses, including NMR spectroscopy and size exclusion chromatography (SEC), confirmed relatively high monomer conversions (up to 86%) and the preparation of polymers with narrow dispersities (Đ ≈ 1.09–1.15). The excellent photo reactivity of Mn₂(CO)₁₀, combined with the intrinsic advantages of continuous-flow processing, enables accurate regulation of residence time, light intensity, and initiator concentration. This work establishes a versatile platform for visible-light mediated polymer synthesis, unifying conventional radical, controlled radical, and cationic processes within a single continuous-flow framework, and highlighting its potential for sustainable, scalable and environmentally benign manufacturing of advanced polymeric materials.