This study describes the synthesis of cadmium sulfide (CdS) modified through green synthesis and doped with oxygen (CdS-O), followed by testing its effectiveness in ciprofloxacin photocatalytic degradation. Green synthesis using tea powder produces smaller CdS particles. Green synthesis using tea powder resulted in smaller particles and oxygen doping, helping to reduce the band gap and increasing its effectiveness in the photodegradation of ciprofloxacin. The synthesized CdS and CdS-O characterized using FTIR, XRD, SEM-EDS, and UV-DRS. FTIR and XRD characterization confirmed the formation of CdS. SEM analysis revealed that CdS particles have a smooth, spherical surface, while CdS-O particles exhibit a coral-like structure. Oxygen doping reduced the band gap of CdS from 2.37 eV to 2.35 eV. The Ciprofloxacin (CIP) degradation results showed that CdS-O achieved a better degradation effect than CdS, with a degradation percentage reaching 58.5%. This highlights the development potential of CdS green synthesis methods and modified enhanced photocatalytic properties for wastewater treatment.