The fluid-powered projectile-assisted injection molding (FPAIM) technique can be used to produce wholly or partially hollowed plastic parts through the introduction of a projectile driven by pressurized fluid. It greatly improves the quality, applications, and design freedom of hollowed parts. The operation principles, variants, advantages and disadvantages, as well as the process factors of FPAIM, are discussed in detail in this paper. In addition, some developments of FPAIM in the areas of both-end openings, projectile, variable cross-section, pipes with branches, closed voids, and elastomeric hollow parts, as well as combinations with other processes, are also introduced. Some applications of FPAIM are briefly presented. Finally, the future development of the FPAIM technique is also discussed.