<p>Uranium is the core material for the development of the nuclear industry, but its irreversible radiation damage poses a significant threat to human health. In this context, an innovative dual-mode colorimetric and electrochemical sensor was developed for the detection of uranyl ions (UO₂²⁺), utilizing a covalent organic framework@gold nanoclusters (AuNCs@COF) composite. The synthesis of AuNCs@COF was simple, and the incorporation of AuNCs imparted the composite with exceptional peroxidase-like catalytic activity and enhanced electrochemical properties. By regulating the adsorption and desorption of aptamers on the AuNCs@COF surface, both peroxidase-like activity and conductivity were modulated, enabling the detection of UO₂²⁺ utilizing colorimetric and electrochemical dual signals. Under optimal conditions, the sensor revealed a broad linear detection range and a low detection limit, with ranges of 1.36 × 10^–10—1.36 × 10^–5&#xa0;mol/L for colorimetric detection and 5.0 × 10^–10—2.5 × 10^–5&#xa0;mol/L for electrochemical detection, achieving detection limits&#xa0;for these two methods&#xa0;of 107 pmol/L and 347 pmol/L, respectively. Unlike other single-mode sensors&#xa0;for UO₂²⁺ detection, this dual-mode sensor demonstrated superior sensitivity, specificity, and repeatability. Furthermore, the results of spiked recovery experiments in real water samples highlight the promising potential of this dual-mode sensor for environmental water monitoring applications.</p> Graphical abstract <p></p>