Nanomaterial biological hybrid systems (NBHSs) integrate photocatalytic nanomaterials with enzymes and microorganisms to couple efficient light harvesting with high biological selectivity. This emerging multidisciplinary approach offers significant potential for solar-to-chemical conversion, yet the fundamental interactions between abiotic nanomaterials and biotic components remain insufficiently understood. This review summarizes recent advances in material–enzyme and material–microbial hybrids with particular emphasis on electron-transfer mechanisms at nano–bio interfaces. It highlights how cytochrome and coenzyme mediated interfacial electron transport enhances synergy, enabling even non-photosensitive bacteria to perform light driven metabolic processes and CO₂ reduction. By outlining key design strategies and mechanistic insights, the chapter provides a foundation for developing next generation NBHSs that support high efficiency energy conversion and contribute to carbon neutral technologies.