Background: Women with breast cancer (BC) have higher risk of developing cardiometabolic conditions compared to women without BC. However, the relationship between healthy eating and onset of cardiometabolic conditions in BC survivors remains unknown. We set out to determine if diet quality at BC diagnosis was related to subsequent development of hypertension, diabetes, and dyslipidemia. Methods: This analysis included 3,415 participants from the Pathways Study, a prospective cohort of women diagnosed with invasive BC (stages I-IV) at Kaiser Permanente Northern California (KPNC) between 2005 and 2013. Food frequency questionnaires were administered at or around the time of BC diagnosis and five diet quality indices (DQI) aligned with healthy eating were evaluated: Dietary Approaches to Stop Hypertension (DASH), a healthy plant-based dietary index (hPDI), 2020 Healthy Eating Index (HEI), American Cancer Society nutrition guidelines (ACS), and the alternate Mediterranean Diet (aMED). Incident hypertension, diabetes, and dyslipidemia were ascertained through electronic health records and participants were followed through first indication of these conditions, disenrollment from KPNC, death, or December 31, 2021. Scores were categorized into ascending quartiles of concordance for each DQI, and multivariable adjusted hazard ratios (HR) and 95% confidence intervals (CI) were estimated. Results: There were 554 (16.2%) incident cases of hypertension, 362 (10.6%) of diabetes, and 652 (19.1%) of dyslipidemia over 39,263 person-years of follow-up. Participants in the highest compared to lowest HEI quartile had lower risks of hypertension (HR=0.70, 95% CI 0.53-0.92, P_trend<0.01), diabetes (HR=0.56, 95% CI 0.40-0.77, P_trend<0.001), and dyslipidemia (HR=0.76, 95% CI 0.59-0.99, P_trend=0.03). Participants in the highest vs lowest hPDI quartile had lower risks of hypertension (HR=0.74, 95% CI 0.55-0.98, P_trend<0.05) and diabetes (HR=0.65, 95% CI 0.46-0.93, P_trend=0.02), but not dyslipidemia. Women in the highest vs lowest DASH and ACS quartiles had lower risks of diabetes (DASH:HR=0.56, 95% CI 0.39-0.79, P_trend<0.001; ACS:HR=0.57, 95% CI 0.40-0.79, P_trend<0.001), but not hypertension or dyslipidemia. No statistically significant differences for aMED were observed between those in the highest vs lowest quartiles. Overall, HRs were similar across DQIs for hypertension and diabetes, except for aMED, which slightly attenuated for diabetes. Conclusions: Diets concordant with HEI may provide the most overall benefit for preventing cardiometabolic conditions after a BC diagnosis. The benefit of diets aligned with hPDI, DASH, ACS, and aMED appear to vary by cardiometabolic condition. Future analyses will examine how these benefits may be modified by BC treatments. Consuming a healthful diet should be recommended to BC survivors for long-term cardiovascular health.