MicroRNAs (miRNAs), a kind of single‐stranded small RNA molecules, play a crucial role in physiological and pathological processes in human beings. We describe here the detection of miRNA, by side‐by‐side self‐assembly of plasmonic nanorod dimers in living cells, which gives rise to a distinct intense chiroplasmonic response and surface‐enhanced Raman scattering (SERS). The dynamic assembly of chiral nanorods was confirmed by fluorescence resonance energy transfer (FRET), also in living cells. Our study provides insights into in situ self‐assembly of plasmonic probes for the real‐time measurement of biomarkers in living cells. This could improve the current understanding of cellular RNA–protein complexes, pharmaco‐genomics, and genetic diagnosis and therapies