The application of nanoparticles (NPs) has been proved as an efficient and promising technique for mitigating a wide range of stressors in plants. The present study elucidates the synergistic effect of iron oxide nanoparticles (IONPs) and silicon nanoparticles (SiNPs) in the attenuation of Cd toxicity in . Seeds of were treated with IONPs (10 mg/L) and SiNPs (20 mg/L). Seedlings of uniform size were transplanted to pots for 40 days. The results demonstrated that nanoparticles (NPs) enhanced growth, net photosynthetic rate, and gas exchange attributes in plants grown in Cd-contaminated soil. Synergistic application of IONPs and SiNPs raised not only K content, but also biosynthesis of polyamines (PAs), which alleviated Cd stress in seedlings. Additionally, NPs decreased malondialdehyde (MDA) content and electrolyte leakage (EL) in plants exposed to Cd stress. These findings suggest that stress alleviation was mainly attributed to the enhanced accumulation of K content, improved antioxidant defense system, and higher spermidine (Spd) and putrescine (Put) levels. It is suggested that various forms of NPs can be applied synergistically to minimize heavy metal stress, thus increasing crop production under stressed conditions.