Micro-Autologous Fat Transplantation (MAFT) represents a transformative evolution in fat grafting, emphasizing precision, safety, and regenerative potential. Rooted in the historical advancements of Drs. Fournier, Carpaneda, and Coleman, MAFT leverages micro-parcel fat delivery (1/60–1/240 mL) to enhance graft survival while minimizing complications such as central necrosis. The MAFT-GUN®, an innovative device designed for precision and consistency, has standardized fat grafting, expanding its clinical applications across aesthetic and reconstructive surgery. Beyond volumetric restoration, MAFT’s integration with adipose-derived stem cells (ADSCs) underscores its regenerative potential in tissue repair and rejuvenation. Clinical evidence highlights its efficacy in periorbital rejuvenation, facial contouring, breast reconstruction, and regenerative medicine for neurology and orthopedics. Complementing the micro-concept, nano-fat extends fat grafting’s therapeutic boundaries by focusing on cellular regeneration without contributing to volume restoration. Typically combined with micro-fat in soft tissue re-volumization, nano-fat enhances outcomes by delivering regenerative effects through its high concentration of stromal vascular fractions (SVFs). This dual-modality approach synergistically addresses both structural augmentation and tissue regeneration, providing comprehensive solutions in aesthetic and functional applications. As regenerative medicine evolves, the micro-concept inspires advancements such as hybrid delivery systems and stem cell enrichment, offering new possibilities for personalized medicine. This chapter explores the scientific rationale, historical progression, practical applications, and future innovations of MAFT, highlighting its indispensable role in modern surgical practice.