As a new two-dimensional nanomaterial, few-layer black phosphorus (BP) shows great potential for many applications. However, owing to its high chemical reactivity, the synthesis and processing of BP must be treated with special care to avoid oxidation-induced degradation. Herein, we explore a facile and efficient liquid exfoliation approach to obtain single- to few-layer black phosphorus nanosheets (BPNSs) with the assistance of Li₂SiF₆. Subsequently, BPNSs were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. Among the conventional solvents, dimethyl sulfoxide (DMSO) was found to provide the BPNSs with a high exfoliation yield (up to 75%). Furthermore, the bacterial toxicity of the BPNSs was evaluated against two model bacterial strains, Gram negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). We believe that this method can provide new opportunities for the preparation of high-quality BPNSs in highly concentrated processes.