Background: This study sought to understand treatment preferences and their association with financial toxicity in breast cancer patients served by Patient Advocate Foundation (PAF). Methods: This cross-sectional study used survey data from a nationwide sample of women with breast cancer who received assistance from PAF. Choice-based conjoint analysis elicited patient preferences and trade-offs. Latent class analysis segmented respondents into distinct preference groups. The Comprehensive Score for Financial Toxicity (COST) tool captured financial toxicity (range 0-44, lower scores indicate worse financial toxicity). Cramer’s V determined magnitude of relationships in bivariate associations. COST score differences by preference archetype was estimated by least square means and naïve 95% confidence intervals (CI) from adjusted generalized linear models. Results: Of 220 respondents (65% response rate), median age was 58 years (interquartile range [IQR] 49-66) and 60% had household incomes < $40,000. Most respondents were diagnosed with early stage cancer (91%), with 41% diagnosed within the past 2 years; 38% had recurred. Almost two-thirds (61%) were on active treatment. Treatment choice was most affected by preferences related to affordability and impact on activities of daily living (ADLs). Two distinct treatment preference archetypes emerged. The “Cost-Prioritizing Group” (75% of respondents) was most concerned about affordability, impact on ADLs, and burdening care partners. The “Functional Independence-Prioritizing Group” (25% of respondents) was most concerned about ability to work, physical side effects, and interference with important life events. Cost- vs. functional independence-prioritizing respondents were more often diagnosed with an early stage cancer (88% vs. 78%; V = .22), white (78% vs. 56%; V = .21), or privately insured (45% vs. 36%; V = .12). Functional independence- vs. cost-prioritizing respondents more often had household incomes < $40,000 (76% vs. 54%; V = .20), identified as Hispanic/Latino (20% vs. 9%; V = .15), or had Medicaid (15% vs. 7%; V = .12). COST scores were similar between archetypes in adjusted models (Cost-Prioritizing COST = 12, 95% CI 9-14; Functional Independence-Prioritizing COST = 11, 95% CI 9-13). Conclusions: Patients with breast cancer prioritized affordability or maintaining functional independence when making treatment decisions. Because of this variability, preference evaluation during treatment decision-making could optimize patients’ treatment experiences.