Abstract Macrophages play crucial roles in protecting our bodies from infection and cancers. As macrophages are multi-functional immune cells, they have diverse plastic subsets, such as M1 and M2, derived from naïve M0 cells. Subset-specific macrophage probes are essential for deciphering and monitoring the various activation of macrophages, but developing such probes has been challenging. Here we report a fluorescent probe, CDr17, which is selective for M1 macrophages over M2 or M0. The selective staining mechanism of CDr17 is explicated as Gating-Oriented Live-cell Distinction (GOLD) through overexpressed GLUT1 in M1 macrophages. Finally, we demonstrate the suitability of CDr17 to track M1 macrophages in vivo in a rheumatoid arthritis animal model.