Nitric oxide (NO) plays a key role in regulating the immune system by polarizing macrophages toward the proinflammatory M1 phenotype, which is beneficial for cancer immunotherapy. We developed a Cu-organic coordination polymer network to sustainably release NO from endogenous donors. This robust polymer network was constructed through a dual-interaction process: complexation and cross-linking. The carboxylate groups of deprotonated 4-((6-(acryloyloxy)hexyl)oxy)benzoic acid (BA) served as bidentate ligands for the formation of Cu(II) complexes. The acrylate moiety of BA anchored these complexes in the polymer network, forming a cross-linked film. Cu ions within the network catalytically promoted NO release from S-nitrosoglutathione, maintaining this release even after 90 days in a physiological environment. The released NO effectively polarized both resting (M0) and tumor-promoting (M2) macrophages to the M1 phenotype. With their demonstrated physiological stability and sustained NO release performance, BA-Cu films hold potential as anticancer patches capable of continuously promoting antitumoral macrophages.