(1) Background: Breast cancer (BC) has a high incidence in Europe, particularly in older adults. Traditionally under-represented in clinical trials, this age group is often undertreated due to ageism. This study aims to characterize frail older adults (≥70 years) with BC based on a comprehensive geriatric assessment, to guide individualized treatment decision-making. (2) Methods: A descriptive analysis of older adults with BC treated from January 2021 to December 2022 was performed. Data were analyzed based on anonymized electronic medical records. (3) Results: Of 123 patients (mean age 84.0 ± 5.6 years), 122 (99.2%) were women. The mean G8 screening score was 12.1 ± 2.5. Most had functional dependence (69.9% Barthel Index, 81.3% Lawton/Brody Scale) and a moderate-to-high risk of falling (76.4% Tinetti index). Cognitive impairment and malnutrition risk were present in 15.4% and 30.1%, respectively. Prehabilitation inclusive strategies led to adapted treatment in 55.3% of cases. Endocrine therapy, surgery, radiotherapy, and chemotherapy was used in 99.2%, 56.1%, 35.0%, and 8.9% of patients, respectively. (4) Conclusions: Our comprehensive oncogeriatric strategy promotes personalized oncologic treatment, improves outcomes by addressing frailty, and enhances treatment tolerability in older patients with BC, validating the expansion of this combined team approach to other cancer types and institutions.