Miniature gears are used in the biomedical, automotive, and aerospace industries for advanced automatic transmission. Significantly few finishing processes can be utilized to finish miniature gears due to the narrow spacing between the miniature gear teeth profiles. In the present study, a novel uniform flow restrictor, an exact negative replica of the miniature gear teeth profiles, is designed and developed while using the rotational magnetorheological fluid-based finishing process. The effect of critical parameters on the process’s performance has been studied through response surface methodology (RSM). The surface roughness and surface texture of the finished gear profiles with different magnetorheological fluids with and without using flow restrictors are compared for consistent and precise finishing. After finishing, it is observed that all manufacturing defects in SS316L miniature spur gear are entirely removed. Also, the ultrafine surface roughness of 23.9 nm (Ra) is achieved using a uniform flow restrictor at miniature gear teeth profiles. The forces responsible for finishing gear profiles are also simulated using Comsol® Multiphysics for understanding the controlling mechanism correctly. A mathematical model for material removal using abrasive grains on gear profiles is carried out to anticipate material dislodgement mechanism during finishing.