Nanomaterials can induce plant tolerance to abiotic environmental stresses, whereas the sensing mechanism and the resulting response at the cellular level need further exploration. Bright Yellow 2 tobacco (Nicotiana tabacum L.) suspension-cultured cells challenged with 100 mM NaCl were exposed to increasing doses (0.05, 0.1, and 0.5 mg L−1) of nano-CeO2 (nCeO2) or nitrogen-doped carbon dots (N-CDs). nCeO2 at 0.1 mg L−1 or N-CDs at 0.5 mg L−1 were optimal for alleviating salt stress and nCeO2 was

superior to N-CDs. Notably, the expression of genes (IPUT1, SOS3, SOS2, and SOS1) involved in Na+-GIPC perception-Na+-extrusion was stimulated (5.3-fold) after nCeO2 exposure for 4 h, and NHX1 encoding Na+ vacuolar sequestration was induced by 7.8-fold after N-CDs treatment for 6 h. Subsequently, the net Ca2+ influx and Na+ efflux were strongly promoted by 293.6% and 191.3% after incubation with nCeO2, while no obvious Na+ extrusion but the transient K+ influx (by 3.0-fold) was observed for N-CDs. The downstream metabolic modifications in fatty acids, or amino acids and carbohydrates could favor the adaptation to salt stress. This work reveals the specific nanomaterial-induced early cell perception and signaling cascade, contributing to the nano-based agricultural practices for combating salt stress.