Nanoporous materials derived from hydrogen-bonded supramolecular liquid crystal complexes present a promising and prevalent perspective in selective adsorption, water desalination, ion conductivity, and so on. However, the specific recognition and selective uptake of some highly self-complementary hydrogen-bonded heterocyclic compounds (e.g., melamine) are extremely difficult for the widely used carboxylic acid-type discotic liquid crystals to competitively bind and remain challenging. Here, we report a nanoporous supramolecular liquid crystal polymeric material built on a photo-cross-linked melamine/thymine-derivative supramolecular structure, which can specifically recognize and selectively absorb melamine from solutions. The small pore diameter, specific hydrogen-bonded sites, and strong systematic binding in the hexagonal columnar nanochannels of the supramolecular polymeric material endow itself with a series of superior properties, including highly competitive uptake of melamine, stable adsorption even in harsh environments, and good adsorption recyclability. Moreover, the melamine adsorption capacity and kinetics of the supramolecular material are also investigated, which determines that the adsorption kinetics of the nanoporous liquid crystal polymeric material follow the Lagergren pseudo-second-order kinetic model.