Purpose Collaborative care between cancer specialists and primary care providers (PCPs) may improve the delivery of high-quality cancer care. Yet, patient perspectives about how involved the PCPs were in their breast cancer care and treatment decisions remain unknown. Patients and Methods A weighted random sample of women newly diagnosed with breast cancer in 2013 to 2014, as reported to the SEER registries in Los Angeles, California, and Georgia, were sent a survey approximately 6 months after diagnosis (N = 2,279, 71% response rate). The distributions of patient-perceived PCP quality (six questions about PCP access and awareness of values) and the following three measures of patient-reported PCP involvement were assessed: how informed the respondent felt her PCP was about her breast cancer (engagement); how often the respondent talked with her PCP (communication); and how often the respondent felt the PCP participated in treatment decisions (participation). Adjusted mean scores of patient-reported satisfaction with and deliberation about the surgical treatment decision were then compared across levels of PCP engagement, communication, and participation using multivariable linear regression. Results The majority of women in this sample perceived high PCP quality (63.6%), high PCP breast cancer engagement (66.2%), and high PCP communication (69.1%). More than a third of women (35.4%) reported that their PCP participated in their treatment decisions. Higher PCP engagement was associated with higher decision satisfaction when compared with low PCP engagement (adjusted P = .003). Conclusion Patient perceptions of PCP quality and PCP involvement in breast cancer care during treatment are high for most women, and PCPs often participate in breast cancer treatment decisions. However, PCP involvement did not lead to meaningful improvements in patients' appraisals of their decision making.