Recently emerging perovskite nanocrystals (PNCs) are very attractive fluorescence nanomaterials due to their very narrow emission peak, tunable wavelength, and extremely high quantum yield, but their chemosensing, biosensing and bioimaging applications suffer from the poor stability of ordinary PNCs in aqueous media, especially in biological matrices. Recently developed water-stable 2D CsPb2Br5-encapsulated 3D CsPbBr3 PNCs (i.e., CsPbBr3/CsPb2Br5 PNCs) show extremely stable light emission in pure water, but their fluorescence is seriously quenched in aqueous media containing biological molecules due to their chemical reactions. In this work, we used a facile method to encapsulate pure water-stable CsPbBr3/CsPb2Br5 PNCs in water with SiO2 and polyethylene glycol hexadecyl ether (Brij58) into a new kind of biological environment-stable PNCs (CsPbBr3/CsPb2Br5@SiO2-Brij58). The synthesis of the target PNCs can be accomplished in a fast, easy, and green way. The obtained CsPbBr3/CsPb2Br5@SiO2-Brij58 PNCs maintain strong fluorescence emission for a long time, all in pH 7.4 PBS, BSA, and minimum essential medium, exhibiting excellent biological environment stability. Moreover, the developed biological environment-stable PNCs show good biocompatibility and have been successfully used in cell imaging. Overall, the work provides an easy, low-cost, and efficient application of PNCs in bioimaging.