In this work, hydrophobic association physical hydrogels were prepared by photoinitiated copolymerization of acrylic acid and butyl acrylate, followed by water immersion. The chemical structure, mechanical properties, self-healing behavior, and self-recovery properties of the physical hydrogels were studied in detail. The hydrogel possessed a large number of carboxyl groups owing to its high content of acrylic acid, and it was used to adsorb cationic dye. Different from brittle chemical hydrogels, the as-prepared physical hydrogels exhibited good tolerance to microwave heating. Thus, the dye-adsorbed hydrogel was successfully applied for microwave-assisted Fenton degradation of cationic dyes. Starting from the unique structure and properties of physical hydrogels, this work successfully explored application scenarios of these systems in dye adsorption and microwave-assisted degradation. The present findings will contribute to understand the relationships among structure, properties, and practical applications of physical hydrogels.