This study investigates the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium *Escherichia coli*. The research was conducted using both liquid systems and agar plates, with energy-filtering transmission electron microscopy (EFTEM) images revealing significant changes in the cell membranes upon treatment, leading to cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action compared to spherical and rod-shaped nanoparticles and Ag+ (in the form of AgNO3). The study suggests that the nanoscale size and the presence of a {111} plane combine to promote this biocidal property. This is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, demonstrating that silver nanoparticles exhibit shape-dependent interactions with *E. coli*. The findings highlight the potential of silver nanoparticles as effective antibacterial agents, with their effectiveness influenced by both size and shape.This study investigates the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium *Escherichia coli*. The research was conducted using both liquid systems and agar plates, with energy-filtering transmission electron microscopy (EFTEM) images revealing significant changes in the cell membranes upon treatment, leading to cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action compared to spherical and rod-shaped nanoparticles and Ag+ (in the form of AgNO3). The study suggests that the nanoscale size and the presence of a {111} plane combine to promote this biocidal property. This is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, demonstrating that silver nanoparticles exhibit shape-dependent interactions with *E. coli*. The findings highlight the potential of silver nanoparticles as effective antibacterial agents, with their effectiveness influenced by both size and shape.