Abiotic stresses such as drought, salinity, heat, and cold pose significant challenges to plant growth and productivity by disrupting cellular homeostasis and triggering the excessive generation of reactive oxygen species (ROS). These ROS, including superoxide radicals, hydrogen peroxide, and hydroxyl radicals, lead to oxidative stress and cause damage to vital cellular components such as proteins, lipids, and nucleic acids. To mitigate these detrimental effects, plants have developed complex defense mechanisms, among which the accumulation of osmolytes plays a crucial role. This chapter explores the pivotal role of osmolytes in ROS scavenging and in maintaining cellular homeostasis under abiotic stress conditions. It begins with an overview of ROS generation and their effects on plant cells, followed by a detailed classification of osmolytes—such as proline, glycine betaine, trehalose, and polyols—and their protective functions. Emphasis is placed on the diverse mechanisms through which osmolytes contribute to oxidative stress tolerance, including direct ROS scavenging, enhancement of antioxidant defense systems, stabilization of macromolecules, and maintenance of redox balance. Furthermore, the chapter examines the regulatory pathways influencing osmolyte accumulation, highlighting transcriptional control, hormonal regulation, and genetic engineering strategies aimed at improving stress resilience in crops. Future perspectives focus on integrating omics technologies and biotechnological approaches to enhance osmolyte-mediated stress tolerance. Through a comprehensive synthesis of current research, this chapter underscores the essential functions of osmolytes in mitigating oxidative stress and maintaining cellular stability, offering valuable insights for the development of stress-resilient crop varieties in the face of global climate change.