Adjusting nucleation conditions, an effective shape and size control in the preparation of single-crystal lithium niobate nanoparticles by aerosol-assisted chemical vapor deposition method was demonstrated. The effect of the most relevant parameters leading to nanocrystals taking a specific shape or size once they are synthesized was analyzed. This has allowed us to demonstrate that it is possible to control the size and morphology of particles prepared adjusting the nucleation conditions. The synthesized nanocrystals showed different morphologies including quasi-cubic, tetrahedral, polyhedral, and hexagonal shapes, with characteristic sizes ranging from a few tens to a few hundred nanometers. However, rod-like structures with characteristic lengths ranging from 3 to 5 μm were also obtained. The structural and morphological characterization by X-ray diffraction and highresolution electron microscopy techniques revealed the single-crystal nature of the synthesized particles.