Salinity stress is an important abiotic stress that negatively affects plant growth and yield as it causes oxidative damage, osmotic stress, and ionic balance disturbances. To overcome these problems, the naturally occurring disaccharide trehalose has received increasing attention due to its multiple roles in functions essential in enhancing plant tolerance to salt. This review examines the current information on how trehalose enhances salinity tolerance, highlighting its biochemical, physiological, and signaling functions. Trehalose scavenges reactive oxygen species and activates important antioxidant enzymes to stabilize cellular structures, maintain osmotic equilibrium, and reduce oxidative damage. Furthermore, it boosts photosynthetic efficiency by maintaining chloroplast integrity and stabilizing photosystems and metabolic enzymes under saline conditions. As climate change increases the severity of salt stress, incorporating trehalose into crop management practices has promising potential to advance sustainable agriculture and ensure global food security. Despite significant progress, the specific mechanisms of trehalose's action, especially its role in signaling pathways and its interactions with other metabolites, remain active research areas. This review explores the potential applications of trehalose in sustainable agriculture while providing a foundation for further research into its mechanisms in regulating plant growth, development, and stress resistance.