Trees experience continuous exposure to climate change, which has become a critical issue worldwide. It accelerates the severity of abiotic stresses, including water deficit, salinity, UV radiation and temperature fluctuations. These changes exert devastating impacts on the progression and development of trees. Long-living trees have evolved different strategies to survive in changing climate. Nitric oxide (NO) is a more focused bioactive compound, and its endogenous synthesis and exogenous application in plants result in several physiological and molecular alterations that help ameliorate adverse impacts of abiotic stresses. NO regulates various stress-responsive gene expressions through comprehensive interconnected signalling pathways such as MAP-kinase-dependent, Ca2+-dependent and phytohormones-dependent signalling. Moreover, NO can modulate antioxidative enzyme activities through post-translational modifications that are positively involved in the tolerance mechanisms. This is crucial for trees to be climate-smart, resilient and more tolerant in a fast-changing environment. NO could be a vital molecule to strengthen plant tolerance and resilience. This chapter addresses different abiotic stresses along with NO-mediated responses to various abiotic stresses.