Smart polymers can distinguish targeted contaminants in water and wastewater. Due to their ability to detect and separate environmental contaminants based on shape-selective capture, stimuli responsiveness, robustness, and cost-effectiveness, smart polymers have been extensively reported in environmental monitoring and sensing applications. One of the important approaches for water quality monitoring and sensing is “molecular imprinting.” In this process, the polymer is synthesized in the presence of the targeted contaminant. After polymerization, the analyte is removed, which leaves behind geometrically specific binding cavities for sensing. Additionally, the recognition ability of smart polymers can be enhanced by immobilizing analyte-specific functionalities such as dyes, fluorophores, and metal nanoparticles. The meritorious advantage of polymer-based materials is their tunable structural and functional properties as per the requirements of the sensing medium. Our studies in the field of molecular imprinting and its application for monitoring and sensing carcinogenic pollutants such as polycyclic aromatic hydrocarbons (PAHs) and cyanotoxins in drinking water are well reported. In this chapter, we present the application of imprinted polymers for monitoring and sensing environmental contaminants in water.