A convenient and sensitive dual-signal visualization method is constructed for detection of trivalent chromium ions (Cr3+) based on fluorescent carbon dots (CDs) and glutathione-modified gold nanoparticles (GSH-Au NPs). The fluorescence of CDs can be quenched by GSH-Au NPs due to the inner filter effect. Cr3+ induces aggregation of GSH-Au NPs because of the coordination with GSH on the surface of Au NPs, leading to the red shift of surface plasmon resonance absorption of Au NPs that provides a "turn-on" fluorescence and colorimetric assay for Cr3+. The fluorescence/colorimetric dual signal detection shows high sensitivity for Cr3+ with wide detection linear ranges (0.5-70μM for fluorescence detection and 2-50μM for colorimetric detection) and low detection limits (0.31μM for fluorescence detection and 0.30μM for colorimetric detection). Besides, the method has high selectivity for Cr3+ and can be used for detection of Cr3+ in lake water and tap water samples, showing great potential for visual detection of environmental Cr3+.