Maintaining clean and fresh pool water requires regular monitoring and treatment. However, the employed methods are manual, complex, and time-consuming. Herein, we proposed a self-sustainable autonomous smart pool monitoring system that can continuously monitor various physio-electrochemical properties of the pool water in real-time without requiring external power. The SPMS includes an electromagnetic generator inspired by the novel Brachistochrone bowl which harvests energy from the random motion (peak power 72 mW at 4 Hz and 0.5 g) and supplies to power the wireless transmission unit and the highly sensitive custom-designed multifunctional sensor unit including pH, temperature, chlorine, conductivity, and wave motion. Each of the fabricated multifunctional sensors has adequate sensitivity and accuracy which can detect minor variations in the water quality for indoor and outdoor environments. Finally, the smart pool monitoring application of the SPMS is demonstrated in real-time by acquiring each of the sensor data and wirelessly transmitting it to the custom-developed mobile application utilizing harvested energy. Combining energy harvesting and water quality sensing, the free-floating completely isolated SPMS device demonstrates a portable, freestanding, wireless, autonomous, and self-powered pool monitoring system for maintaining a hygienic and safe swimming environment.