As a result of anthropic pressures, such as industry, deforestation and waste disposal, soil contamination is increasing and, consequently, compromising soil functions and fertility. Among all contaminants, metals are one of the most common and important, being able to negatively affect the growth and development of plants. Thus, new and innovative ways to counteract the adverse effects of metals on plants are urgently needed. Nanotechnology, an emerging field in technological sciences, offers multiple tools that can be used for this purpose. In this way, this work aimed to evaluate the potential of Fe2O3 nanoparticles (NPs) to alleviate metal-induced stress in Hordeum vulgare L. (barley plants). For this goal, plants grew under two metal-contaminated soils (S1 and S2) of Estarreja (Aveiro, Portugal) treated and non-treated with 1% (w/w) Fe2O3 NPs. After 14 days of growth, biometric parameters (root length and fresh biomass) were evaluated, along with the analysis of several biochemical endpoints [photosynthetic pigments, lipid peroxidation (LP) and hydrogen peroxide (H2O2)]. After exposure to S1 and S2 contaminated soils, plant development was greatly affected, as evidenced by significant decreases in root length and fresh weight of roots and leaves. However, upon cotreatment with Fe2O3 NPs, this phytotoxicity was partially recovered, with less inhibitory effects on biometric parameters, especially in S1. This pattern was also noticed for levels of total chlorophylls and carotenoids. Regarding the oxidative damage, both S1 and S2 led to increases in LP, though H2O2 levels were only increased in S2. In response to the co-treatment with Fe2O3 NPs, barley plants exhibited less oxidative damage, which is evidenced by the decrease of H2O2 and LP in both soils. Altogether, the present study revealed that Fe2O3 NPs are able to enhance the tolerance of barley plants to contaminated soils, possibly by limiting the occurrence of oxidative stress.