Newly emerging perovskite nanocrystals (NCs) have shown a huge potential to be utilized in a gamut of optoelectronic devices due to their superior photoluminescence quantum yield (PLQY), tunable emission wavelength, and facile synthesis protocols at low cost. Despite the enormous progress made in synthetic protocol development, their poor stability against environmental stressors remains a major shortcoming that significantly restricts their practical applications and future commercialization. Of particular interest, core/shell NC engineering has fueled significant progress not only to improve the luminescent properties, reduce exciton recombination, suppress non-radiative recombination, and enhance the charge carrier transport but also, perhaps more importantly, to improve the semiconductor materials’ stability under harsh environmental conditions. Accordingly, this architecture represents a promising avenue to alleviate the stability issue and, therefore, could push the devices’ operational stability and performance forward. In this Focus Review, we explore the successes and challenges of recently reported perovskite core/shell heterostructures and summarize the synthesis methods, the photophysics after shelling, the theoretical approaches, and the applications. Finally, we conclude with a discussion of new opportunities and suggestions to push this research area a step forward.