Wheat is one of the most widely cultivated crops worldwide, ranking first in area and fourth in production. It is the second most important cereal for human consumption after rice and for feed after maize. However, its growth is increasingly affected by abiotic stresses such as salinity, mainly caused by inadequate agricultural practices and saline irrigation. Another environmental concern is the large volume of toxic wastewater from olive oil mills (OMW). Recovering this waste is key to reducing environmental impact and supporting the circular economy. Based on this current issue, the objective of this study is to evaluate OMW as a potential biostimulant for wheat grown under salinity conditions. To achieve this, a greenhouse experiment was carried out in which wheat plants (Triticum aestivum L.) were grown under controlled conditions, and three different doses of OMW (0.050, 0.125, 0.25 mM of phenolic compounds) were applied via foliar. The plants were treated with OMW both under saline (100 mM NaCl) and normal conditions. Under non-saline conditions, the highest OMW dose led to a 15% increase in stem length and a 17% in fresh weight compared to the untreated control. Additionally, this treatment resulted in a 20% higher protein concentration and improved membrane stability by 6%. In contrast, the two lower concentrations did not produce significant changes in growth parameters and remained similar to the non-saline control. Under saline conditions, plant growth was reduced in all treatments, and OMW applications did not counteract salt stress. Although the two highest OMW doses under salinity increased protein and proline levels, they did not improve fresh weight or stem length. While higher OMW concentration improved growth and physiological traits under non-saline conditions, no enhancement in growth was observed under salt stress, suggesting that an alternative OMW pretreatment or modified application strategies should be considered.