Background The latest National Comprehensive Cancer Network Breast Cancer Guidelines still discourage repeat sentinel node biopsy (SNB) after mastectomy, and the largest multicentric study available reports only 35 cases in the absence of previous axillary dissection (AD). Methods From January 2003 to November 2018, 89 patients of the European Institute of Oncology with local recurrence of breast cancer after mastectomy, free of distant metastases, with a clinically negative axilla and a negative axillary ultrasound, in absence of AD, underwent lymphatic mapping before wide local excision. Results During surgery, SNB was successful for 99% of the patients, with 14% being metastatic. Additional metastatic nodes removed by AD after a positive sentinel node occurred in 82% of cases. After a medium follow-up period of 3.7 years, the overall survival rate was 96.7%, and the disease-free survival rate was 84.4%. No axillary relapse after AD was recorded. One patient who refused human epidermal growth factor receptor 2 (HER2)-targeted treatment experienced ipsilateral axillary recurrence after a negative repeat SNB. The first axillary level was never directly irradiated because all the patients with positive repeat SNB underwent AD. For invasive luminal-like HER2-negative recurrences, the metastatic sentinel node was significantly associated with the choice to prescribe adjuvant chemotherapy ( p  = 0.003). Conclusions In specialized centers, repeat axillary SNB for patients with local recurrence after mastectomy in the absence of previous AD can represent a safe option for detection and removal of occult axillary disease that would otherwise not be excised/irradiated to achieve better local control and could possibly influence the choice of adjuvant treatments.