<p>Sugars, the core products of plant primary metabolism, not only serve as energy sources and carbon skeleton, but also act as key signaling molecules that regulate multiple aspects of plant growth, development, and stress responses. Global climate change has intensified abiotic stresses including drought, extreme temperatures, salinity, and hypoxia, making the elucidation of sugar-mediated stress tolerance mechanisms critical for sustainable agriculture. Under these stresses, plants reprogram sugar metabolism and signaling networks to maintain energy homeostasis, activate stress responses, and balance growth with stress adaptation. Here, we summarize the core properties of sugars as both nutrients and signaling molecules, and systematically elaborate their specific functions and underlying molecular mechanisms in plant abiotic stress responses. We discuss critical knowledge gaps in sugar-mediated abiotic stress signaling. We aim to provide a theoretical basis for in-depth mechanistic dissection of sugar-mediated plant abiotic stress tolerance, and practical guidance for the molecular breeding of abiotic stress-tolerant crop varieties.</p>