Abstract Soils of arid and semi-arid environments are prone to salinization and boron toxicity. However, limited studies have been dedicated to investigating interactive effects of these stressors on plants. This study evaluates growth, water relations, and osmoregulation of 30-day-old Pistacia vera seedlings in response to combinations of different concentrations of NaCl (0, 800, 1600, and 2400 mg kg−1) and boron (0, 2.5, 5, and 10 mg kg−1) in soil under controlled environment conditions for 120 days. The treatments were arranged as a factorial experiment based on completely randomized design. Separate applications of 1600–2400 mg NaCl or 20 mg kg−1 soil reduced plant biomass and growth rate, due to development of water deficit, plasma membrane injuries, and decline of water use efficiency. Application of 10 mg kg−1 soil prevented plant growth inhibition under 800–1600 mg kg−1 soil. Under severe NaCl stress, however, 5 mg kg−1 soil was the best treatment for improving performance of the plants. The ameliorating effects of soil boron amendments on NaCl stress was due to improving osmoregulation via enhancement of glycine betaine accumulation, improvement of water availability to the plant, and reduced cell membrane injuries. On the other hand, boron toxicity pressure reduced under 800–1600 mg kg−1 soil treatments, which was mainly due to stomatal closure, limitation of transpiration rate, and reduced boron accumulation in shoot. These observations revealed that soil boron level largely influences plant responses to salt stress, and soil boron amendment can improve salt tolerance of P. vera.