The objective of present research work is to investigate the surface morphology, physical and mechanical properties of unidirectional S-glass fiber epoxy composites filled with varying amount of ZnO nanofiller content such as 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt% respectively. ZnO nanofiller was modified with matrix in varying amount using mechanical stirrer and followed by ultrasonication process. The laminate composites were fabricated using a compression molding press technique. Further, laminate composites were subjected to individual characterization and testing in an according to American society for testing and materials standards. The crystalline nature of ZnO nanofiller was studied using X-ray diffraction analysis and surface morphology of ZnO nanofiller on the resin surface was examined by using a scanning electron microscope. The experimental test results revealed that addition of nanofiller content by 1 wt%, 2 wt% and 3 wt% resulted in a gradual reduction of a void fraction by 2.760%, 2.510% and 1.641% respectively and thereafter growth in void fraction increased from 2.696% to 2.833% with 4% and 5 wt% of loading. The flexural and impact strength increased to a maximum of 694.2 MPa and 2550.42 J/m with 3 wt% of loading, with further increasing load content of 4 wt% and 5 wt%, both flexural and impact strength were decreased. Whereas, surface microhardness results showed unique behavior in increased order of 21.6 HV, 24.3, 28.5, HV 33.7 HV and 38.4 HV with nanofiller loading of 1 wt% to 5 wt%. Thermo-gravimetric test analysis of composites revealed that there was negligible weight loss (%) in composites at 50 ˚C to 380 ˚C. So, composites were thermally stable up to 380 ˚C. Further heating of composites from 380 ˚C to 900 ˚C, the majority of weight loss (%) incurred in composites which were nearly half of the weight loss (%).