Woody and fruit trees undergo various abiotic stresses throughout their life cycle, which can lead to the accumulation of reactive oxygen species (ROS) and subsequent oxidative damage. ROS, including superoxide anion radical, hydrogen peroxide, hydroxyl radical, and singlet oxygen, are byproducts of oxygen metabolism and can cause severe damage to cell membranes and organelles. Plants have evolved enzymatic and non-enzymatic antioxidant systems to scavenge ROS and maintain cellular homeostasis. However, severe and long-term nutrient deficiency, drought, high-temperatures, and salinity can overwhelm plant defense mechanisms, leading to oxidative stress, which impairs growth and development. Nutrient deficiencies, like nitrogen, phosphorus, iron, and magnesium, induce ROS formation and activate antioxidant enzymes such as superoxide dismutase, catalase, and peroxidases. Drought stress leads to photosystem imbalance, accumulation of osmolytes, such as proline, and the activation of antioxidant defenses. High-temperatures increase transpiration rates and decrease water use efficiency, while salinity increases toxic ions (Na+ and Cl−) and ROS. Understanding the mechanisms of ROS production and scavenging in woody and fruit trees is crucial for developing strategies to enhance their tolerance to these abiotic stresses. This review discusses the current knowledge of ROS accumulation and antioxidant defense systems in woody and fruit trees under various abiotic stresses, as well as potential strategies for improving their resilience to environmental challenges.