As signaling molecules, hydrogen peroxide (H₂O₂) and nitric oxide (NO) cooperate in physiological and biochemical reactions and exhibit significant overlap in their pathways. A wide range of abiotic stresses can induce H₂O₂ and NO synthesis, and there is a complex interactive network among H₂O₂ and NO in plants. Moreover, a number of reports have shown that pre-treatment of plants with exogenous H₂O₂ and NO confer abiotic stress tolerance. This review aims to introduce the physiological and molecular mechanisms by which exogenous H₂O₂ and NO induce adaptation of plants to stressful environments. This is useful in order to adjust plants to the changing environment for sustainable agricultural development. We also discuss the crosstalk among H₂O₂ and NO signaling, which regulates plant growth and development, as well as responses to abiotic stresses.