Abstract Cu doped LaCoO 3 photocatalyst by microbial synthesis (M-LaCo 0.7 Cu 0.3 O 3 ), using the extract of Pichia pastoris GS115, presents an outstanding photocatalytic performance for hydrogen production from formaldehyde solution. The structure and physicochemical properties of the photocatalyst were characterized by XRD, EDS, XPS, FTIR, Photoluminescence (PL), and UV–vis (DRS). The results indicate that copper doping contributes to the formation of impurity level and appropriate oxygen vacancy. Differing from separate citric acid complexation with metal ions, biomass intervention in preparation process can help adjust the crystal structure and surface structure of catalyst, which makes the diffraction angle and unit cell change and simultaneously modulates surface oxygen defects. Furthermore, some organic functional groups from biomass residue on the surface act as photosensitizer, so that the M-LaCo 0.7 Cu 0.3 O 3 markedly absorbs the visible light and shows higher absorbance than LaCo 0.7 Cu 0.3 O 3 and LaCoO 3 . Consequently, M-LaCo 0.7 Cu 0.3 O 3 exhibits the highest rate of photocatalytic hydrogen production (1.13 mmol h −1 g −1 ). This research provides a new way for designing and developing visible-light active materials using biomass.