<p>Nano-fertilizers are being extensively analyzed for better crop growth and high yield production. This field experiment was conducted to assess the impact of soil applied CuS nanoparticles (NPs) and CuSO₄ (as control) on the growth and yield of <i>Sesamum indicum</i>. FTIR, GC–MS and, ¹H and ¹³C NMR techniques were used to determine the functional groups and fatty acid profile of <i>S</i>. <i>indicum</i> oil. CuS NPs resulted in notable improvement in root length (27.95%), shoot length (18.47%), branches/plant (73.54%), dry weight per plant (37.02%), fruits/plant (41.33%), seeds/fruit (50.95%) and oil percentage (23.74%) of <i>S</i>. <i>indicum</i> compared to control. Antioxidative enzymes activities, phenolic and flavonoid contents in plants mildly increased to dispose NPs generated oxidative stress assessed by free radical scavenging activity, total reducing power, and total antioxidant capacity. GC–MS identified seven fatty acids in oil samples with minor changes in fatty acid profile, with higher saturated and lower unsaturated fatty acid in treated plant’s oil. The ¹H NMR and ¹³C NMR analyses demonstrated no substantial alterations in the chemical composition of <i>S</i>. <i>indicum</i> oils. These findings suggest that Cu-based NPs treatments do not change the structural integrity or key functional groups of the oil but increase overall production of oil. Therefore, CuS NPs holds promising potential in improving the growth and yield of <i>S</i>. <i>indicum</i>, highlighting their role as elicitor as well as nanofertilizer in modern agricultural practices.</p> Graphical abstract <p></p>