Single-molecule localization microscopy (SMLM) is one of the most promising super-resolution imaging techniques for visualizing ultrasmall cellular structures. Here, water-dispersed perovskite CsPbBr3 nanocrystals (CsPbBr3 NCs) fabricated by a one-step mechanochemical method are explored as a SMLM fluorophore for bioimaging. Due to their ultrahigh photoluminescence quantum yield (PLQY), inherent frequent fluorescence blinking, proper duty cycle and long-term photostability, an extremely high location precision of ∼3 nm was achieved, a sixfold enhancement than those reported previously. In addition, the spatial resolution of a SMLM image depends on the size of CsPbBr3 NCs, which is approximately 23 nm. Two closely spaced CsPbBr3 NCs with a gap of 40 nm can be clearly distinguished in the SMLM image. More importantly, unlike most perovskite quantum dots (QDs), one-step mechanochemically prepared CsPbBr3 NCs can retain their excellent fluorescence characteristics even after surface biofunctionalization, greatly reducing the current limitations of perovskite QDs on bioimaging. As an example, cell-derived exosomes (30-150 nm in diameter) labeled with CsPbBr3 NCs were easily identified by SMLM. In addition, after being functionalized with biotin, targeted SMLM imaging of the nuclear lamina or cell membranes of cells was achieved with an enhanced resolution. This work may open up a promising avenue to expand the field of perovskite QD-based SMLM to bioimaging with a high location accuracy.