The rapid global rise of antimicrobial resistance (AMR) that increasingly invalidates conventional antibiotics has become a huge threat to human health. Although nanosized antibacterial agents have been extensively explored, they cannot sufficiently discriminate between microbes and mammals, which necessitates the exploration of other antibiotic-like candidates for clinical uses. Herein, two-dimensional boron nitride (BN) nanosheets are reported to exhibit antibiotic-like activity to AMR bacteria. Interestingly, BN nanosheets had AMR-independent antibacterial activity without triggering secondary resistance in their long-term use and displayed excellent biocompatibility in mammals. Surface proteome analysis coupled with molecular dynamic simulations and Bio-Layer Interferometry revealed that BN nanosheets could rapidly interact with the key surface proteins of cell division including FtsP, EnvC, and TolB, resulting in a specific antibacterial mechanism by impairment of Z-ring constriction in cell division. Notably, BN nanosheets had a potent antibacterial effect in a lung infection model by P. aeruginosa (AMR), displaying a two-fold increment of survival rate. Overall, these results suggested that BN nanosheets could be a promising nano-antibiotic to combat resistant bacteria and prevent AMR evolution.