Cellular heterogeneity characterises normal physiology as well as driving disease progression, therapeutic resistance, and variable clinical outcomes. Single-cell technologies address such complexities by enabling molecular and functional analysis at the level of individual cells, but are fundamentally limited by low analyte abundance, perturbation during handling, and loss of spatial context. Nanotechnology provides powerful solutions to these challenges by enabling precise single-cell generation, manipulation, and ultra-sensitive analysis at biologically relevant length scales. This chapter reviews advances in nanotechnology-enabled single-cell platforms, spanning nano-engineered cell isolation and handling, single-cell genomics, transcriptomics, proteomics, and spatial and functional multi-omics. We highlight translational applications across oncology, immunology, and therapeutic development, including nano-enabled drug response profiling, imaging, and targeted delivery. Together, these approaches position nanotechnology as a key driver of next-generation single-cell biology, enabling mechanistic insight and clinical translation from bench to bedside.