We investigated the ability of a novel triazatruxene–rhodamine-based (TAT-ROD) chemosensor to detect the trivalent metal ions aluminium (Al3+), iron (Fe3+) and chromium (Cr3+). Operating via the through-bond energy transfer (TBET) pathway, the chemosensor exhibited low detection limits of 23.0, 25.0 and 170.0 nM for Al3+, Fe3+ and Cr3+, respectively, along with high sensitivity and selectivity during a brief period (<15 s). The binding ratio of the chemosensor and trivalent metal ions achieved by Job's method was 3:1, and when we added ethylenediaminetetraacetic acid (EDTA), the sensing process reversed. Altogether, our TAT-ROD chemosensor marks the first triazatruxene-based colorimetric and fluorometric metal ion sensor reported in the literature. [ABSTRACT FROM AUTHOR]