Abstract Heterojunction engineering in nanomaterials has been a cornerstone of research in diverse fields owing to its profound impact on charge transport and interfacial properties. However, despite recent insights suggest that precise control over the heterostructures is critical for optimal functionality, a universally guideline defining the optimal heterostructures remains elusive. Herein, we proposed a novel “electroactive model guidance” approach to guide the nanostructures design in redox‐active conductive metal‐organic frameworks (c‐MOFs) based p‐n heterojunction for high performance photocatalyst. Chosen Cu 2 O@c‐MOFs core‐shell heterostructures as model, we optimized the shell thickness based on a mathematical electroactive model. The optimized structure achieved a tenfold photocurrent enhancement compared to pristine Cu 2 O—a record‐high for heterojunctions. The heterojunctions with optimal shell thicknesses exhibited outstanding degradation efficiency for tetracycline, with a catalytic degradation efficiency up to 99.35% and exhibited the rate constant of 0.065 min −1 , this represents the highest rate constant, reported to date for such systems. Furthermore, the universality of this theoretical model extends to other c‐MOFs, such as Cu‐OHPTP and Cu‐DBC, which similarly exhibit significantly enhanced performance. This work not only provides a robust framework for the rational design of redox‐active semiconductor heterojunction but also offers valuable insights into optimizing their functional properties for advanced applications.