Among engineered nanomaterials designed for sustainable crop production, water-soluble fullerene derivatives offer unique properties with broad biological applications. In this paper, the role of fullerenol in amelioration of iron (Fe) deficiency (the most common and widespread nutrition disorder) in Cucumis sativus (a Strategy I plant) was investigated. Cucumber plants were grown hydroponically, either with [+Fe^II (ferrous) and +Fe^III (ferric)] or in Fe-free (−Fe^II and −Fe^III) nutrient solution, with (+ F) or without (−F) a fullerenol supply. Being higher in root apoplastic Fe, the –Fe^II plants became less chlorotic and were more tolerant to Fe deficiency, as compared with –Fe^III plants. Although fullerenol did not affect the root apoplastic Fe in Fe-fed plants, it significantly lowered the root apoplastic Fe in –Fe^II-starved plants, in turn, increasing the leaf active-Fe concentration and successful suppression of plant Fe-deficiency symptoms. The ameliorative effect of fullerenol was accompanied by a significant increase in leaf fluorescence parameters: maximum efficiency (Fv′/Fm′) and electron transport rate (ETR), indicating that fullerenol addition activated reaction centres of PSII in the Fe-deprived plants. The results suggest for the first time that fullerenol can protect cucumber plants against Fe deficiency through increased utilisation of root apoplastic Fe.