ZnFe₂O₄ is an n-type semiconductor spinel oxide with promising applications in various fields, including photocatalysis. This study reports the successful synthesis of a novel ZnFe₂O₄ derivative based on Prussian Blue Analogues (PBAs) through an electrosynthesis method. To enhance photocatalytic performance, the synthesized ZnFe₂O₄ was employed as a cocatalyst in p–n junction materials, specifically CuO/ZnFe₂O₄. Our findings reveal that introducing ZnFe₂O₄ could significantly improve the photocatalytic activity and hydrogen (H₂) production rate of the CuO/ZnFe₂O₄ system compared to bare CuO. This enhancement was sustained over an extended operational period, indicating the material’s potential for long-term use in photocatalytic applications. The superior performance of the ZnFe₂O₄ cocatalyst is attributed to its efficient charge separation and improved light absorption properties, which collectively contribute to higher photocatalytic efficiency. This study highlights the potential of PBA-based derivative ZnFe₂O₄ as an effective cocatalyst in developing advanced photocatalytic systems for sustainable hydrogen production.