Hydrogen sulfide (H₂S), known for its unpleasant rotten egg smell and its high toxicity, has recently emerged as an important mediator of human physiological and pathological processes, such as the regulation of cell growth, cardiovascular protection, the stimulation of angiogenesis, gastric mucosal injury and Alzheimer's disease. Due to its significant actions in the physiology, H₂S has attracted the abundant concern of numerous researchers in the cutting edge of chemistry, biology and medicine. Recently, several fluorescent probes have been developed for detecting and elucidating the role played by H₂S in biological systems. This review highlights recent advances that have been made on the mechanism and applications of fluorescent probes for the detection of H₂S, demonstrating a new field in which remarkable improvements have been accomplished over the last two years.