Catalytic hydrogenation/dehydrogenation of carbon nitrogen bonds (–CH–NH–, –C=N–, –C≡N) represents fundamental transformations in synthetic chemistry and hydrogen storage. While significant advances have been made in hydrogenation or dehydrogenation individually, reversible interconversion using a single catalyst remains challenging. To address this challenge, we develop a copper-coordinated porous organic polymer (POP) catalyst featuring binuclear bis(imino)pyridine coordination units (dibis(imino)pyridine). This dibis(imino)pyridine-based POP catalyst could reversibly mediate both the dehydrogenation transformation of benzylamine compounds and the hydrogenation transformations of nitriles. Remarkably, both transformations proceed efficiently under mild conditions (water solvent, ≤ 80 °C) in the absence of precious metals, while demonstrating excellent catalytic recyclability with consistent product yields across successive cycles.