Silver nanomaterials (AgNMs) ubiquitously known for their biological applications are studied here in terms of their shape-dependent antibacterial and anti-biofilm effect. Chemically synthesized nano-cubes (AgNCs) with size range around 150–200 nm were compared for their biological activity with commercial nano-sphere (AgNS) of comparable size (${\sim}$160 nm). The antibacterial activity against both Escherichia coli and Staphylococcus aureus showed higher activity for nano-cubes compared with nano-spheres.The synergistic role of AgNMs with antibiotic ampicillin was also found promising. A four times enhancement and an increase of nearly 25% of antibiotic activity at 0.0625 mg ml$^{–1}$ concentration was found with 0.05 mg ml$^{–1}$ of AgNCs in agar and broth media, respectively. Anti-biofilm effect towards E. coli and S. aureus was also evaluated. AgNCs showed equal importance in biofilm disruption with 20% inhibition activity, which was yet again found better in-comparison with AgNSs. The study shows that AgNCs with distinct faces and edges could show efficient anti-bacterial effect and so such intelligently designed material could pave path for imminent medical challenges.