The detection of nucleic acid is critical for clinic diagnostics. Single-nanoparticle inductively coupled plasma mass spectrometry (SP-ICPMS) has demonstrated unique advantages for nucleic acid detection. Here we report the development of a novel SP-ICPMS DNA assay based on a target-induced hybridization chain reaction to achieve controlled spherical nucleic acid assembly. The assembly process generated large gold nanoparticle aggregates, and the number of aggregates could be counted by SP-ICPMS, which was closely correlated to the concentration of the target DNA. This simple homogeneous assay could analyze DNA within the range of 5 fM to 10 pM with excellent selectivity and applicability for real sample analysis. It is envisioned that the developed approach might create a useful SP-ICPMS platform for biomolecule detection.