Mitochondria, crucial intracellular organelles, are central to energy metabolism, signal transduc-tion, apoptosis, calcium homeostasis, and a myriad of other biological processes, making them a focal point in diverse research fields. The capacity to fluorescently labeling and visually track mitochondria is crucial for understanding their biological roles. We present Mulberrin-Cy3, a novel small molecule fluorescent probe that selectively labels mitochondria in animal cells, in-cluding cancer cells, with relative ease. This protocol details the synthesis of Mulberrin-Cy3 and its use for visualizing mitochondria in living cells. The synthesis is straightforward and time-efficient, and the labeling method is more accessible than traditional approaches, providing a cost-effective option for mitochondrial visualization at room temperature. The labeling is rapid, with effective labeling achieved within 5 minutes of incubation. The fluorescent signal is stable and brighter, offering a significant advantage over existing methods. Mulberrin-Cy3 represents a promising mitochondrial labeling compound, providing researchers with a novel experimental tool to explore the complex biological functions of mitochondria. This innovation has the potential to significantly advance our comprehension of mitochondrial dynamics and their role in cellular health and disease.