Purpose: Regular primary care may be important to prevent ambulatory care-sensitive hospitalizations among older individuals living with breast cancer. The current study aimed to examine the relationship between preventable hospitalizations and primary care among Medicare beneficiaries diagnosed with breast cancer. Methods: We used SEER-Medicare to identify 61,673 patients with incident stage 0-III breast cancer diagnosed between January 1, 2008, and December 31, 2015. Potentially preventable hospitalizations, defined using the Agency for Healthcare Research and Quality, were captured from diagnosis until death, second malignancy, or December 31, 2016. Primary care and non-oncology specialist visits were identified by distinct utilization groups (low utilizers vs. high utilizers). Incidence rate ratios [IRR]) were estimated for preventable hospitalizations. Multivariable Cox regression models estimated the association of primary care with 5-year overall survival. Results: Median age at diagnosis was 74 years (range 66–101), median follow-up was 46 months (12–60), and 5-year survival was 82%. Over half of patients (59%) received primary care ≥ 1 time per year, and 7.8% had no primary care. Among low utilizers, no primary care was associated with a 55% increase in the rate of preventable hospitalizations (p < 0.001). Primary care was not associated with preventable hospitalizations among high utilizers. Factors associated with hospitalization for both high and low utilizers included higher stage at diagnosis, older age, and having a preventable hospitalization prior to cancer. Not receiving any primary care was associated with higher risk of 5-year mortality for low utilizers (HR 1.66, p < 0.001; HR 1.46, p < 0.001). Conclusions: Among the group with less utilization, not engaging annually with a primary care provider was associated with a significantly increased rate of preventable hospitalizations. Implications for Cancer Survivors: Consistent engagement with primary care may provide an opportunity for care coordination and management and should be considered critical in the context of long-term survivorship.