Of late agricultural productivity across the globe has been driven by overwhelming limitations imposed by fluctuating environmental stress caused by climate change. A central common theme among environmental stresses is serious impact on redox biology and the perturbation of the redox homeostasis in crop plants. Crops exploit an elaborate redox system for responding to environmental fluctuations and acclimation. Redox Biology offers insights into the formation of ROS, its detox scavenging, sensing, role in oxidative deterioration, and signalling associated with redox-regulatory physiological processes of plant. ROS-antioxidant interaction at metabolic interface found to regulate cellular redox cue, metabolism, development, differentiation, stress signaling, interactions with other growth factors, systemic responses in crops. Crop plants are equipped with antioxidative defence systems not only to combat enhanced level of ROS, but also to tightly regulate the endogenous concentration necessary for controlling various events of Plant Biology. The ROS wave which is a consequence of perception of unfavourable environmental cues, thought to be integrated with additional metabolic/signalling pathways to enable rapid systemic acclimation of organisms. In recent times, as an approach to engineer climate resilient crops, many strategies have been used to explore the positive signalling role of ROS while restricting their negative impact on crop system biology. The presentation will try to illustrate the physicochemical basis of the production of ROS, under normal and unfavourable environmental conditions, their sensing mechanisms, with an added effort to understand their implication associated with stress tolerance and signalling and existing redox-based strategies to improve crop performance under stress. Further, glimpses of the work my laboratory will be presented to discuss the central role of internal redox cue under abiotic stress as determinant of oxidative stress response, emphasizing how redox cue has opened up new avenues to exploit redox biology for crop improvement required for sustainable food security.