Purpose: Cadmium (Cd) is amongst the most toxic heavy metals which severely affects the plant growth. Application of nanoparticles (NPs) could be helpful to negate the deleterious impacts of Cd stress in crop plants. Methods: In this study, seed priming of two fragrant rice cultivars, i.e., Xiangyaxiangzhan and Yuxiangyouzhan, applied with four levels of Lanthanum oxide nanoparticles (La2O3NPs) i.e., 0, 50, 100, and 300 mg L–1, grown under three Cd levels i.e., 0, 50, and 100 mg L−1. Result: Results revealed that the nano-priming with La2O3significantly improved the seed germination rate under the Cd stress. Nano-priming exhibited substantial improvements in the total fresh weight, shoot length, root length, leaf sheath length and prophyll leaf length under the Cd stress. Moreover, nano-priming with La2O3NPs substantially modulate the antioxidant activities i.e., superoxide dismutase, peroxidase, and catalase, and enhanced the α-amylase activity. Nano-priming further reduced the malondialdehyde, metallothionein, glutathione, proline, and soluble protein contents whilst enhanced the chlorophyll and carotenoids contents. Conclusions: Seed priming with La2O3NPs substantially enhanced the early growth of rice seedlings by improving morphological attributes and modulating the physiological and biochemical responses under Cd toxicity. The insights gained from this study may be of assistance to understand the effects of La2O3NPs on early growth of rice, and its potential applications in enhancing the Cd tolerance of crops.