Industrial wastewater containing organic dyes poses severe threats to the global aquatic ecosystem. The exploration of low-cost and environmentally friendly adsorbents has become one major task for the fast and effective elimination of organic dye contaminants. In this study, we fabricate a new type of polymeric dye adsorbent (P1) by crosslinking bihydrazide-functionalized pillar[5]arene with trimesoyl chloride as linkers. Benefiting from the π-electron rich cavity of pillar[5]arene, P1 has demonstrated outstanding potential in the selective adsorption and separation of small cationic dyes. Kinetic experimental results prove that the adsorption behaviors for methylene blue (MB) and neutral red (NR) are accurately matched with the pseudo-second-order model and Freundlich isotherm model. In addition, the integral adsorption rate is determined by both external diffusion and intra-particle diffusion. The pillararene-based polymer adsorbent can be recycled five times with almost no loss of adsorption efficiency, holding great potential to function as an available material for wastewater regeneration and purification.