Background: Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 has affected over 100 million individuals during the current pandemic. Cancer is a reported risk factor for worse outcomes from SARS-CoV-2 infection and its clinical syndrome COVID-19. However, risk associated with specific cancer subtypes, extent of disease, and treatment history remains unclear. Breast cancer is the most common cancer in women and is treated with multiple modalities that may affect COVID-19 severity and outcomes, including surgery, radiation (RT), hormone therapy (HT), and chemotherapy (CT). Methods: We conducted a retrospective cohort study of patients with SARS-CoV-2 and history of breast cancer at two academic centers in Los Angeles, CA between January - September, 2020. Demographic information, cancer diagnosis, treatment history, comorbid conditions, and clinical outcomes of COVID-19 were reviewed. The primary outcome was rate of hospitalization for COVID-19. Associations were evaluated for significance by chi-square test or Student's T test, with a = 0.05. Results: Our cohort included 61 patients with history of breast cancer. 19 (31.1%) required hospitalization and 3 (4.9%) died from COVID19. Median age was 61 years. 44% of patients were White/Caucasian, 37.7% Hispanic/Latinx, 8% Black/African American, 5% Asian, and 5% were of another race. 87% of patients had local or regional disease and 13% had distant metastases. 53% of patients had ever received CT historically, 66% HT, and 53% RT. 25% of patients received cancer treatment (surgery, CT, or RT) within 90 days of COVID-19 diagnosis. 38% were on HT at time of COVID-19 diagnosis. Patients with prior RT were more likely to be hospitalized from COVID-19 than those with no prior RT (44% vs 14%, p = 0.02), as were patients with 2 or more comorbidities (p = 0.01). In addition, there was a trend toward lower hospitalization rates for patients on HT [24% vs. 42% (p = 0.17)] and a trend toward higher hospitalization rate for non-white ethnicity [35% vs. 25% (p = ns)]. Extent of disease, history of CT, or receipt of any cancer treatment (e.g. surgery, RT, CT) within 90 days of COVID-19 diagnosis were not associated with hospitalization rate. Conclusions: In our diverse cohort of breast cancer patients with COVID-19 a history of RT and presence of multiple comorbidities were both associated with increased risk of hospitalization, while a history of HT was not. Further investigation is needed to validate these findings in larger cohorts. These findings may inform recommendations for breast cancer patients during the ongoing SARS-CoV-2 pandemic.