Excessive caloric intake and reduced energy expenditure contribute to obesity and localized fat accumulation, adversely affecting overall health. Despite advancements in obesity treatments, noninvasive approaches for targeted fat reduction remain limited. This study introduces a novel sonosensitizer microparticle, cerium-doped calcium carbonate (CaCO(3):Ce), and evaluates its potential application in combination with low-intensity ultrasound (LIUS) for noninvasive body sculpting. CaCO(3):Ce was synthesized via an environmentally friendly method, producing uniform 1.77 μm particles optimized for endocytosis. Energy-dispersive X-ray and X-ray photoelectron spectroscopy confirmed successful cerium doping. The particles demonstrated excellent biocompatibility and generated reactive oxygen species under LIUS exposure. Safety was validated through biochemical, hematological, and histological analyses in Sprague-Dawley rats. Animal experiments further revealed that CaCO(3):Ce combined with ultrasound significantly reduced body weight growth rates, waistline measurements, and subcutaneous fat accumulation. These findings suggest that CaCO(3):Ce, coupled with LIUS, offers a promising, noninvasive, and low-risk strategy for body sculpting, addressing limitations of current methodologies.