Single cell analysis has become a crucial goal since cellular heterogeneity was acknowledged as one of the greatest challenges in cancer therapeutics. Radioactive probes can play an important role in single cell study thanks to its unique capability of tracking small molecules with minimal modification of their chemical structure. Our lab has recently developed a new technique known as radioluminescence microscopy (RLM) to measure the amount of radiotracer in single cells. Yet, RLM can image only up to about 100 cells and lacks capability of integrating with subsequent sample processing such as cell sorting. Here we introduce a robust, high throughput single cell radiometry based on radiofluorogenesis and droplet optofluidics. As an example, we quantitated [18F]-fluorodeoxyglucose radiotracer uptake in single human breast cancer cells and assessed cellular heterogeneity in single cell metabolism.