Nitroaromatic compounds, for example trinitrotoluene and 2,4,6-trinitrophenol (TNP), are well-known primary constituents of many unexploded landmines worldwide. These compounds are recognized as environmental contaminants and as toxic to living organisms. Therefore, Förster resonance energy transfer (FRET) for TNP detection was developed on the basis of spectral overlap between the fluorescence spectrum of copper nanoclusters (CuNCs) and absorption spectrum of TNP (the calculated Förster distance R 0 of the donor CuNCs and the acceptor TNP is 2.8 nm). Water-soluble fluorescent CuNCs capped with bovine serum albumin have fluorescence emission from 350 nm to 500 nm with maximum fluorescence emission at 400 nm, which overlaps with the absorption spectra of TNP from 350 nm to 450 nm. Inspired by FRET structures, an unprecedented energy-donor-and-acceptor pair of fluorescent CuNCs and TNP is developed in this work. Fluorescence of CuNCs is quenched in the presence of TNP as a result of FRET from fluorescent CuNCs to TNP. Therefore a fluorescence quenching method for the determination of TNP is developed. It achieves TNP detection from 0.8 μmol L(-1) to 100 μmol L(-1), with response within 1 min and with good selectivity compared with that for other nitroaromatic compounds, including 2,4-dinitrotoluene, p-nitrotoluene, and nitrobenzene, and phenol. Graphical Abstract Förster resonance-energy-transfer detection of 2,4,6-trinitrophenol using copper nanoclusters was first developed. It achieves TNP detection from 0.8 mmol L(-1) to 100 mmol L(-1) within 1 min with good selectivity compared with other nitroaromatic compounds.