Herein we report superior dye-degradation performance for polyaniline-silver (PANI-Ag) nanoparticle coated on polystyrene (PS) electrospun membrane by in situ-polymerization method. Morphological study of the coated membrane shows PANI-Ag nanofibril network with average diameter of 100 nm around micrometer diameter electrospun PS fiber. X-ray diffractogram (XRD) showed the formation of PANI-Ag nanocomposite and according to Bragg's reflection the crystal diffraction plans are from the FCC structure of Ag. Thermal analysis of the composite reveals glass transition temperature observed in the temperature range from 100 -110 degrees C for both PANI and PANI-Ag coated samples and 5 % residue is left after heating it to 800 degrees C, which may be due to presence of Ag in the composite. Antimicrobial study indicates that pure PANI sample do not exhibit any antibacterial performance for both Staphylococcus aureus and Escherichia coll. However, antibacterial behavior is observed for PANI-Ag samples when experiment is performed. The photocatalytic degradation of AZG dye solution using PS/PANI-Ag membrane shows 85 % of AZG dye degraded within 180 min. The stability check of the nanocomposites is done by FTIR analysis PS/PANI-Ag nanocomposite is not affected and no chemical transformation takes place during the photodegradation process.