In recent years, synthesis of nanoparticles using natural materials is the essential constituent in the medicinal and clinical laboratory due to inexpensive, recyclable and without use of toxic chemicals. In this present work, SW-Ag/ZnO nanoparticles were synthesized by simple in situ chemical precipitation approach. Padina gymnospora was taken as a bio-surfactant material for preparing Ag nanoparticles and these are further intercalated with ZnO particles. The synthesized nanoparticles were charecterized and confirmed by Fourier transform infra-red spectroscopy, X-ray diffraction analysis, UV-Visible Diffuse reflectance spectroscopy, High resolution scanning electron microscopy and Transmission electron microscopy techniques. The SW-Ag/ZnO was appeared in large clusters with different shaped particles, the size of them was obtained in 14-40 non. Seaweed capped Ag/ZnO particles showed the greater UV protection values achieved the 45.2% than RSW and SW-Ag. Thermal degradation characteristics of SW-Ag/ZnO have greater thermal stability than RSW and SW-Ag nanoparticles. Moreover, the photocatalytic degradation performances of nanoparticles were tested under the sunlight irradiation using phenol pollutants. Their photocatalytic degradation reaction was well fitted with the first order reaction kinetics. In addition, the antimicrobial activity of nanoparticles was also tested against (Gram (+ ve) and Gram (-ve) microbial pathogens and it could be exhibited the higher bacterial inhibition activity obtained for SW-Ag/ZnO than that of RSW and SW-Ag nanoparticles.