This study demonstrates the first example of a highly efficient photoinduced miniemulsion Atom Transfer Radical Polymerization (ATRP) driven by red or near-infrared (NIR) light. The process is facilitated by the use of methylene blue (MB⁺) as a water-soluble photocatalyst, which efficiently excites MB⁺ under red/NIR light, leading to the photoreduction of the ATRP deactivator in the presence of water-soluble electron donors. This results in the initiation and mediation of the polymerization process. The NIR-driven miniemulsion photoATRP provides a successful synthesis of polymers with low dispersity (1.09 ≤ D ≤ 1.29) and quantitative conversion within an hour. The study also explores the impact of light penetration on polymerization kinetics in reactors of varying sizes and a large-scale reaction (250 mL), highlighting the advantages of longer-wavelength light, particularly NIR light, for large-scale polymerization in dispersed media due to its superior penetration. This work opens new avenues for robust emulsion photopolymerization techniques, offering a greener and more practical approach with improved control and efficiency.This study demonstrates the first example of a highly efficient photoinduced miniemulsion Atom Transfer Radical Polymerization (ATRP) driven by red or near-infrared (NIR) light. The process is facilitated by the use of methylene blue (MB⁺) as a water-soluble photocatalyst, which efficiently excites MB⁺ under red/NIR light, leading to the photoreduction of the ATRP deactivator in the presence of water-soluble electron donors. This results in the initiation and mediation of the polymerization process. The NIR-driven miniemulsion photoATRP provides a successful synthesis of polymers with low dispersity (1.09 ≤ D ≤ 1.29) and quantitative conversion within an hour. The study also explores the impact of light penetration on polymerization kinetics in reactors of varying sizes and a large-scale reaction (250 mL), highlighting the advantages of longer-wavelength light, particularly NIR light, for large-scale polymerization in dispersed media due to its superior penetration. This work opens new avenues for robust emulsion photopolymerization techniques, offering a greener and more practical approach with improved control and efficiency.