As the human population continues to escalate, its requirement for clean water is also increasing. This has resulted in an increased dependency on wastewater effluent to maintain the base flow of urban streams, especially in water-stressed regions. The present study reports the synthesis of AgNPs with green credentials using an aqueous extract of Trigonella foenum-graecum seeds. The observance of surface plasmon resonance (SPR) with UV−Vis spectrophotometry confirmed the presence of spherical/oblong particles with a mean diameter of 43.8 nm and low polydispersity index (PDI) of 0.391 measured by transmission electron microscopy (TEM) and DLS (dynamic light scattering) technique, respectively. The elemental map of AgNPs was demonstrated with energy-dispersive spectroscopy (EDS) and the constituent functional groups were identified by the FTIR spectra, which were similar to the bulk seed extract with a slight shift in the pattern. The emission spectrum of nanoparticles was recorded for the excitation wavelength of 349 using fluorescence microscopy and the crystalline structure was assessed using X-ray diffraction. The potential wastewater remedial efficacy of the synthesized AgNPs was evaluated based on the water quality parameters (pH, EC, BOD, COD) of the sewage effluent collected from a local Sewage Treatment Plant (STP). Furthermore, the photo degradative efficacy was investigated using the degradation percentage of Crystal Violet (CV) dye, which was recorded as 94.5% after 20 min. In addition, the antimicrobial activity of the NPs versus bulk seed extract was assessed against two bacterial strains, Escheria coli and Staphylococcus aureus, using the disc diffusion method. The AgNPs showed a profound modulatory effect on the water quality parameters, coupled with marked antimicrobial and photodegradative activity. Thus, the biogenically synthesized AgNPs offer a prospective potential for use in wastewater remediation strategies.