The ability to capture alterations in the genome or transcriptome by next-generation sequencing has provided critical insight into molecular changes and programs underlying cancer biology. With the rapid technological development in single-cell sequencing, it has become possible to study individual cells at the transcriptional, genetic, epigenetic, and protein level. Using single-cell analysis, an increased resolution of fundamental processes underlying cancer development is obtained, providing comprehensive insights otherwise lost by sequencing of entire (bulk) samples, in which molecular signatures of individual cells are averaged across the entire cell population. Here, we provide a concise overview on the application of single-cell analysis of different modalities within cancer research by highlighting key articles of their respective fields. We furthermore examine the potential of existing technologies to meet clinical diagnostic needs and discuss current challenges associated with this translation. Keywords: cancer research; clinical diagnostics; clinical utility; single-cell sequencing.