Peroxynitrite (ONOO-) is attracting increasing attention due to its involvement in multiple facets of pathophysiological processes. However, ONOO- bioimaging is still challenging due to (1) the lack of highly specific reaction triggers, (2) the tedious and low-yielding synthesis of current sophisticated probes, and (3) the lack of availability of a versatile chemical strategy. To address these challenges, on the basis of amine formylation/deformylation chemistry, we have developed a novel strategy for ONOO- bioimaging. As proof of principle, we designed, synthesized, and evaluated four novel fluorescent probes equipped with the formamide functionality. Although they feature distinctly different fluorophore classes, all probes can be synthesized in one step in high yields and exhibit particularly specific, highly sensitive, and rapid responses to ONOO-. The bioimaging capability is well demonstrated by successfully visualizing ONOO- fluctuation in live cells and major organs of mice suffering from paraquat poisoning. The proposed strategy has proved to be a facile, versatile, and highly efficient methodology for ONOO- visualization, which will greatly facilitate ONOO- biochemistry and pathophysiology.