<p>The detection of nitroaromatic compounds (NACs) is critically important due to their extensive use in explosive materials and the associated environmental and security risks. In this work, three structurally tailored coumarin derivatives 6-chloro-4-(4-methoxyphenoxymethyl)-chromen-2-one (S1), 1-(4-methoxyphenoxymethyl)-benzo[f]chromen-3-one (S2), and 6-methoxy-4-(4-methoxyphenoxymethyl)-chromen-2-one (S3) were explored as fluorescent probes for NAC sensing in Dimethyl sulfoxide (DMSO). Steady-state absorption, emission, and time-resolved spectroscopic investigations revealed significant fluorescence quenching upon gradual addition of nitrobenzene (NB), 2-nitrotoluene (2NT), 4-nitrotoluene (4NT), and 2,4,6-trinitrophenol (TNP). Stern–Volmer (S-V) analysis displayed positive deviations for NB, 2NT and 4NT, suggesting a combined dynamic and static quenching mechanism, whereas negative deviations observed for TNP indicates the major contribution from dynamic quenching mechanism. Fluorescence lifetime measurements confirmed dynamic quenching as the dominant pathway. Thermodynamic analysis revealed negative free energy change (ΔG_PET) of the photoinduced electron transfer (PET) values for all coumarin–NAC systems, establishing the favourable nature of the PET process. Among the probes, S2 exhibited superior sensing performance owing to its extended π-conjugation and enhanced donor characteristics, resulting in the highest Stern–Volmer constants and quenching efficiencies. Both solution mode and contact mode studies demonstrated practical applicability, with S2 achieving the lowest detection limit for TNP (2.55 × 10⁻⁶ M). Overall, these findings highlight the potential of rationally designed coumarin derivatives as efficient, cost-effective, and selective fluorescent sensors for nitroaromatic detection, particularly for TNP.</p>