In this article, we report on the preparation of ultrasmall SnS nanoparticles embedded in carbon spheres (called SnS/C nanocomposite) by one pot aerosol spray pyrolysis and its application as a high-rate and long-cycle life anode material for sodium-ion batteries. The structure and morphology analysis of the as-prepared nanocomposite shows that SnS nanoparticles with a size about 5 nm are homogeneously dispersed in the carbon spheres (denoted as 5-SnS/C). The sizes and components of SnS particles can be controlled by adjusting the precursor's concentration. When applied as an anode material of sodium-ion batteries, the 5-SnS/C nanocomposite delivers an initial charge capacity of 560.8 mA h g⁻¹ at 1 A g⁻¹ and maintains a reversible capacity of 517.6 mA h g⁻¹ after 200 cycles at 1 A g⁻¹. In particular, the 5-SnS/C electrode exhibits a high-rate capability, with reversible capacities of 428.5 mA h g⁻¹ at 3 A g⁻¹ and 315.4 mA h g⁻¹ at 5 A g⁻¹, respectively. The excellent electrochemical performance of 5-SnS/C is due to the fact that the uniformly embedded ∼5 nm SnS nanoparticles in the stable carbon matrix can alleviate the volume expansion during cycling with a buffering effect to prevent aggregation of SnS nanoparticles.