<p>Carbon dots (CDs) have emerged as versatile carbon nanomaterials owing to their tunable optical properties, abundant surface functional groups, excellent chemical stability, low toxicity, and facile synthesis. Their integration with metals, metal oxides, polymers, and other carbonaceous materials has led to the development of multifunctional composites with enhanced physicochemical and functional properties. This review summarizes the major synthesis strategies for CD-based composites, including hydrothermal, microwave-assisted, pyrolytic, biomass-derived green synthesis, and in situ reduction methods, and examines their influence on material performance. Particular emphasis is placed on carbon dot–silver (CDAg) nanocomposites for catalytic and antibacterial applications, based on studies reported between 2015 and 2026. Among the reported systems, the AgNPs/NCDs nanocomposite synthesized by Reddy et al. exhibited the highest catalytic activity, achieving 99.95% reduction of 4-nitrophenol under ambient conditions, while antibacterial studies revealed minimum inhibitory concentration (MIC) values as low as 26&#xa0;µg&#xa0;mL⁻¹ against bacterial strains. The superior performance of these nanocomposites is attributed to synergistic interactions between CDs and silver nanoparticles, which enhance charge transfer, increase the density of active sites, and promote reactive oxygen species generation. Mechanistic insights into catalytic pollutant degradation and antibacterial action, including membrane disruption and silver ion release, are discussed, along with emerging applications in fluorescence and electrochemical sensing. Finally, key structure–property–performance relationships, current challenges, and future research directions are highlighted to guide the rational design of advanced CD-based nanocomposites for environmental, biomedical, and sensing applications.</p> Graphical abstract <p></p>