Bio-hydrothermally synthesized ZnO nanoparticles (NPs) were coated ex situ on degummed silk fibers and subjected for X-ray diffraction, Scanning Electron Microscopy, and Energy dispersive spectroscopic characterization. Both coated and/uncoated fibers were sterilized by autoclave and ethylene oxide. Effect of coating and sterilization on mechanical properties of fibers was evaluated measuring its tensile strength. Antibacterial efficacy of coated fibers was assayed against Staphylococcus aureus. PXRD of uncoated and ZnO NPs coated fibers fairly differ, with former exhibiting highly amorphous nature and latter showing additional ZnO peaks at 34.42 degrees and 36.41 degrees corresponding to (002) and (101) planes with decreased amorphousness. SEM demonstrated spherical and agglomerated NPs on entire fiber surface and EDS confirmed presence of Zn. Coated fibers had significant improvement in tensile strength, measuring 2.2 N/m(2) against 0.82 N/m(2) of uncoated silk fibers. Autoclaving affected tensile strength of both coated and uncoated fibers detrimentally though coated fibers showed better resistance. Antibacterial activity of coated fibers was excellent on day 2 (1.9 cm zone of inhibition), which gradually declined by 6th day showing that coated fibers have consistent antibacterial activity against S. aureus. Hence, coating with ZnO NPs caused improvement in mechanical properties and antibacterial properties of degummed silk fibers, which could be a potent biomaterial for biomedical applications.