There is great demand for nanoparticles (NPs) dispersed in liquid phases for practical applications of functional NP materials. However, it is difficult to produce NP dispersions with specific particle sizes, concentrations, viscosities, and purities on an industrial scale (large mass production rate and low energy consumption). In this review, we highlight recent developments in NP dispersion using low-energy bead mill. Such processes enable the use of small beads (7–50 μm). Smaller beads reduce the collision and shear energies of NPs during agitation. This minimizes NP breakage/damage, and retains the shape and crystallinity of the NPs, which determine the inherent NP functions. This review starts with a brief explanation of the theory and current status of NP dispersion and describes the mechanism and experimental results for low-energy bead mill processes, i.e., using uniaxial, dual-axial, and all-separator bead mills, and selection of dispersing agent. Applications of NP dispersions, including nanocomposite materials, and methods for dealing with NP dispersion coloration are also discussed, along with future research directions.