This study evaluates the impact of hyaluronic acid (HA) injection for nipple projection following mastectomy, as a complement to areola micropigmentation. While micropigmentation is standard in nipple-areola complex (NAC) reconstruction, HA use remains novel, with limited data on psychosocial, sexual, and aesthetic outcomes. A sequential explanatory mixed-methods design will be used. In Phase 1, a randomized controlled trial will compare two groups: one receiving NAC micropigmentation alone (control) and the other receiving micropigmentation plus HA-based nipple projection (intervention). A total of 138 participants will be recruited at the Areolar Micropigmentation Unit of Germans Trias i Pujol University Hospital (Barcelona) over 36 months. Outcomes will include psychosocial and sexual well-being, satisfaction with breast and nipple appearance, and nipple projection, measured using the Spanish BREAST-Q, a custom satisfaction tool, and calipers. Phase 2 will involve a qualitative phenomenological study using semi-structured interviews with a purposive sample from the intervention group. Thematic analysis will explore body image, emotional and social well-being, and overall satisfaction, using NVivo software. This is the first study assessing HA nipple reconstruction by advanced practice nurses using validated patient-reported outcomes. While the BREAST-Q is appropriate, it may not fully capture emotional nuances, justifying qualitative exploration. HA durability is estimated at 6-9 months, but residual volume and satisfaction over time remain underexplored. HA's aesthetic footprint may allow reduced dosages in future applications. This minimally invasive technique may reduce the need for surgical nipple reconstruction. Conducting the procedure in a nurse-led setting is novel and may enhance patient-centered care and the role of nursing in post-mastectomy recovery. The study complies with the Declaration of Helsinki and Spanish biomedical regulations. Ethical approval was obtained. Participants will provide informed consent, and data will be anonymized and securely stored.