Hydrazine, a compound recognized for its carcinogenic and genotoxic properties, presents a significant threat to human health via environmental exposure and drug metabolism. The detection of hydrazine is essential for safeguarding human health. However, a tool capable of accurately detecting hydrazine across diverse sample types, such as soil, water sources, and plant specimens contaminated by hydrazine leakage, as well as cells and live mice containing endogenously generated hydrazine from drug metabolism, is still lacking. In this study, we have designed and synthesized a ratiometric fluorescent probe utilizing the fluorescence resonance energy transfer mechanism. Upon exposure to hydrazine, the probe exhibits an increased fluorescence ratio (F485 nm/F650 nm) accompanied by a color change from orange to light blue-green. The fluorescence sensing mechanism has been validated through high resolution mass spectrometer and density functional theory. This probe demonstrates significant potential for practical applications in detecting hydrazine within water and soil samples, as well as for imaging exogenous and drug-metabolized endogenous hydrazine in cellular and murine models.