The industrialization, growing population, and human activities (e.g., liquid waste of households, industrial units, and agricultural lands) are the main causes to contaminate fresh water sources. To overcome this issue, many techniques have been applied for water purification and chemical oxidation is one of the effective ways to treat the wastewater called as advanced oxidation process (AOPs). In the present study, synthesized silver phosphate nanoparticles were employed as catalysts in the photocatalytic advanced oxidation process for the degradation of various dyes (RhB, MB, MO, and OG) and drug (SMZ). The photocatalyst was characterized through different analytical tools, e.g., PXRD, FTIR, UV-Vis DRS, DLS, FESEM, and HRTEM. The chemical behavior or interaction of dye molecule with catalyst surface has also been explored to understand the mechanism of photodegradation reaction. All the organic dyes and drugs showed pseudo first-order rate kinetics and it was found that RhB dye and SMZ drug degraded so fast by the photocatalyst. The maximum observed photodegradation rate was 0.0744 min for SMZ drug and 0.0532 min for RhB dye, respectively. The minimum dye degradation was observed ~ 0.0036 min for OG, which is ~ 15 times lesser than the degradation rate of RhB dye. From the comparative dye degradation study, it was found that the photodegradation efficiency of organic pollutants depends on the surface charge of the photocatalyst. The role of photogenerated reactive species (holes, superoxides, and hydroxyl free radicals) was also studied using different types of scavengers which helped to understand the photochemical reactions and mechanism by photocatalyst. The real sample analysis of textile effluent was also performed using the best photocatalyst in the presence of light.