AbstractMultiparametric single‐cell analysis has seen dramatic improvements with the introduction of mass cytometry (MC) and imaging mass cytometry (IMC™). These technologies expanded the number of biomarkers that can be identified simultaneously by using heavy‐isotope‐tagged antibody reagents. Small‐molecule probes bearing heavy isotopes are emerging as additional useful functional reporters of cellular features. Realizing this, we explored the iodination of DAPI to produce a heavy‐atom‐substituted derivative of the commonly used fluorescent DNA stain. Although exhibiting a drastically reduced fluorescence emission profile, I‐DAPI retains strong binding affinity for DNA. I‐DAPI was used to detect cellular DNA in MC and IMC™ assays with comparable efficiency to known Ir‐containing DNA intercalators. This work suggests repurposing well‐known colorimetric stains through simple reactions could be an effective strategy to develop new, functional MC and IMC™ reagents.