Background: Cancer treatment and its sequelae have been associated with financial toxicity in breast cancer survivors, particularly those who have no health insurance. However, the prevalence of financial toxicity in the insured survivors, and the underlying factors are not well understood. Methods: Breast cancer survivors attending a survivorship clinic (University of Alabama at Birmingham) completed a survey assessing demographics, financial toxicity (i.e., material resources; food/housing/energy insecurity), and health-related quality of life (HRQL: SF-36). Clinical characteristics were abstracted from medical records. A multivariable logistic regression model was developed to understand factors associated with financial toxicity; the model included survivor age, race, socioeconomic status, insurance type, marital status, cancer stage, time since diagnosis, current medications, and physical and mental domains of HRQL. Results: The 368 participants (1% male; 67% white, 25% African American, 8% other) were a median of 61y of age (range, 33-86y) and 4.3y post-diagnosis (1-34y) at survey completion; 90% had stage 0-II disease; 34% were single (not currently married/partnered); type of health insurance included private/military (57%), Medicare (39%), and Medicaid/self-pay (4%). Overall, 31% reported financial toxicity; 26% endorsed not being able to live at current standard of living > 2 mo. if they lost all current sources of income; 6% endorsed energy insecurity, 5% endorsed food insecurity, and 4% endorsed housing insecurity. In a multivariable model, financial toxicity was associated with age ≤60y at survey (Odds Ratio [OR] 5.1; 95% confidence interval [CI] 2.0-13.3); household income < $50K/y (OR 5.3; 95%CI 2.5-11.2); being single (OR 2.6; 95%CI 1.3-5.4); and lower physical (OR 2.6; 95%CI 1.2-5.4) and mental (OR 2.2; 95%CI 1.2-4.3) HRQL. Cancer stage, race, time from diagnosis, and insurance type were not associated with financial toxicity. The prevalence of financial toxicity among survivors who were single, ≤60y at survey, and with household income < $50k/y was 79.3%, compared with 6.7% among those who were older, married/partnered, and with higher income. Conclusions: Financial toxicity is prevalent among insured breast cancer survivors several years after cancer diagnosis, and is exacerbated among the younger survivors who are single, with low household income, and endorse poorer physical and mental quality of life. These findings inform the need to develop interventions to mitigate financial toxicity among at-risk breast cancer survivors.