Well-dispersed barium titanate (BaTiO3; BT) with an average primary particle size < 200 nm and lattice tetragonality 1.010, being very close to that of a BT single crystal, was obtained via a solid-state route with the aid of preliminary dry mechanical processing. The latter treatment not only activates the starting mixture but also decreases the particle sizes of individual ingredients and increases the homogeneity. All these favor to suppress grain growth of the product BT due to increasing nucleation site density, easing the nucleation at the given nucleation site, and decreasing the diffusion paths. These were confirmed by (i) microscopy and particle size analysis to observe downsizing of individual particulates without causing agglomeration; (ii) electron probe microanalysis to reveal increase in the homogeneity in a few micrometer regime; and (iii) X-ray photoelectron spectroscopy to reveal mechanochemical effects across the solid-solid boundary of dissimilar particles.