The rigorous synthetic methodologies have significantly impeded the progress in developing single-crystal extended organic polymers. Notably, the existence of macroscopic single-crystalline 2D porphyrin-based organic polymers has never been documented in the literature until now. In this study, we present a groundbreaking example of single-crystal 2D porphyrin-based organic polymers that are compatible with single-crystal X-ray diffraction (SXRD) for precise structural elucidation. Their formation is fundamentally dependent on the synergistic assembly facilitated by dative B─N bonds and halogen bonds. These crystals exhibit remarkable stability in both air and aqueous environments. Notably, the formation of the B-N Lewis pairs within these crystals significantly enhances the separation of photogenerated carriers, and their single crystals demonstrate exceptional photocatalytic activity for the production of hydrogen peroxide (H