Dye pollution is one of the more recalcitrant problems in industrial wastewater management. Over 700,000 tonnes of synthetic dyes are manufactured globally each year with a significant fraction discharged from textile mills, tanneries, printing facilities, and chemical plants into wastewater. The aromatic ring systems and chromophoric structures that give dyes their colour also make them chemically inert under most natural degradation conditions. Conventional treatment plants, designed primarily around biological processes, tend to leave dye contamination largely intact. The downstream consequences are well-documented: impaired water quality, toxicity to aquatic organisms, and gradual accumulation in sediments and receiving waters. This study examines the potential of heterogeneous Fenton-like systems through the use of metal-doped carbon dots (CDs) for the decolourisation of the dyes methylene blue and rhodamine blue in wastewater. Fe-, Cu-, Zn-, and Mg-doped CDs were synthesised hydrothermally and characterised— transmission electron microscopy placed particle sizes in the 10.2–15.2 nm range, while FTIR, XPS, and Zeta-potential measurements confirmed that dopant identity alters surface chemistry and interfacial charge. Performance-wise, Fe-doped CDs showed the greatest decolourisation of the dye Methylene blue (k = 0.0218 min⁻¹), probably due the role of Fe²⁺/Fe³⁺ cycling in activating H₂O; In contrast, Zn-doped CDs showed the highest rates of decolourisation of Rhodamine blue— a finding that appears linked to their negative surface charge and the density of oxygen-containing groups, both of which favour dye adsorption and ROS production. Cu- and Mg-doped CDs each behaved in ways consistent with their respective redox and adsorption profiles. Overall, the results confirm that dopant choice is not interchangeable; it meaningfully determines how the catalyst behaves. Temperature and oxidant concentration were found to be the dominant factors in determining rates of decolurisation; however, optimal conditions were not transferable between dopants. Fe- and Cu-doped CDs performed better at higher temperatures with relatively modest H₂O₂ inputs; Zn-doped CDs needed more oxidant but were less temperature-dependent. Metal-doped CDs synthesised through straightforward hydrothermal methods represent a viable option for integration into advanced oxidation treatment systems — and possibly not only for dyes.