Poly-3-hydroxybutyrate (PHB)-derived plastics are polymer materials with excellent biodegradability, being insoluble in water and relatively resistant to hydrolysis. There is a need for a method capable of synthesizing 3-hydroxybutyrate, a monomer of PHB, from a renewable material. In this work, visible-light driven 3-hydroxybutyrate from CO₂ and acetone with the system consisting of triethanolamine, water-soluble zinc porphyrin, pentamethylcyclopentadienyl coordinated rhodium complex, NAD⁺ and a cell extract containing acetone carboxylase and 3-hydroxybutyrate dehydrogenase from Rhodobacter capsulatus SB1003 cultured in acetone-bicarbonate medium is established. In particular, the conversion yield for acetone to 3-hydroxybutyrate was improved up to 81% in this system after 7 h irradiation.