The main objective of this study was to compare the effectiveness of PRO, an innovative foliar multi-component fertilizer, with TRA, a fertilizer of standard formulation. TRA contained macronutrients (N, P, K), micronutrients (B, Cu, Fe, Mn, Mo, Zn, with Fe and Zn complexed with EDTA), and trace elements (Cr, I, Li, Se in mineral form). PRO had the same quantitative composition, but Fe and Zn were complexed with amino acids, and trace elements were combined with plant extracts. For PRO fertilizer, the effect of a two- and three-fold increase in application rate above the standard rate was additionally studied. Experiments were carried out on oilseed rape cultivated in a growing hall on two different soil types (loamy and sandy). The applied fertilizers significantly increased seed and straw yields of spring oilseed rape. The key determinant of yield was soil type. Both fertilizers showed comparable effectiveness, although higher doses of PRO resulted in more pronounced yield increases. The beneficial effect of fertilization was observed on both soil types, with particularly strong plant responses noted on sandy soil. The concentration of certain macro- and microelements also increased after foliar fertilization. Among microelements, the highest percentage increases relative to unfertilized plants were recorded for iron (in both seed and straw) and for manganese and copper in straw. The highest concentrations of microelements were recorded after applying higher doses of PRO. Of the trace elements, only lithium and selenium showed significant increases. In summary, the use of multi-nutrient foliar fertilizers represents an effective strategy for improving oilseed rape yield and quality, as well as a valuable tool for the biofortification of plants with essential nutrients.