Breast lipofilling, also known as fat grafting (AFG) or autologous fat transfer (AFT), has gained increasing attention for its natural and minimally invasive approach to breast augmentation and reconstruction. Thus, this chapter provides an in-depth exploration of AFG as a minimally invasive technique for breast augmentation and reconstruction. The development of specialized processing techniques such as CELT (Cell-Enriched Lipotransfer) and Cell-Enriched Lipotransfer Purified Long-lasting Ultra-concentrated Supergraft (CELT-Plus) has further enhanced precision, graft survival, and overall outcomes in both aesthetic and reconstructive breast surgeries. This chapter delves into the intricate details of the CELT and CELT-Plus methods, their applications, fat harvesting, processing techniques, and fat injection layers. We explore where fat is injected into the different breast layers, how these layers are prepared, and how the use of appropriate cannulas impacts clinical success. Special attention is given to the multi-layered anatomy of the breast and how each layer responds to fat grafting.