This review discusses the development of flavin-dependent 'ene'-reductases (EREDs) as biocatalysts for non-natural radical reactions. The study highlights the versatility of EREDs in catalyzing asymmetric reductions and radical cyclizations, with a focus on their ability to control stereochemistry through precise electron transfer mechanisms. The research explores both ground-state and photoexcited states of flavin, demonstrating how these states can be harnessed to initiate and terminate radical reactions. Key findings include the use of EREDs for hydrodehalogenation, radical cyclization, and intermolecular radical reactions, showcasing their potential for enantioselective and regioselective transformations. The study also addresses the challenges of substrate scope and reaction efficiency, proposing strategies such as directed evolution and photoexcitation to enhance catalytic performance. The results demonstrate that EREDs can achieve high yields and selectivity in various radical reactions, offering new avenues for biocatalytic applications in pharmaceutical and agrochemical synthesis. The work underscores the importance of enzyme engineering and the unique capabilities of flavin-dependent enzymes in enabling complex radical chemistry.This review discusses the development of flavin-dependent 'ene'-reductases (EREDs) as biocatalysts for non-natural radical reactions. The study highlights the versatility of EREDs in catalyzing asymmetric reductions and radical cyclizations, with a focus on their ability to control stereochemistry through precise electron transfer mechanisms. The research explores both ground-state and photoexcited states of flavin, demonstrating how these states can be harnessed to initiate and terminate radical reactions. Key findings include the use of EREDs for hydrodehalogenation, radical cyclization, and intermolecular radical reactions, showcasing their potential for enantioselective and regioselective transformations. The study also addresses the challenges of substrate scope and reaction efficiency, proposing strategies such as directed evolution and photoexcitation to enhance catalytic performance. The results demonstrate that EREDs can achieve high yields and selectivity in various radical reactions, offering new avenues for biocatalytic applications in pharmaceutical and agrochemical synthesis. The work underscores the importance of enzyme engineering and the unique capabilities of flavin-dependent enzymes in enabling complex radical chemistry.