Background Nutritional quality, and health and climate impacts are important considerations in the design of sustainable diets. Objectives To investigate the association between diets varying in nutrient density and climate impact and MI and stroke HRs. Methods Dietary data of 41,194 women and 39,141 men (35–65 y) who participated in a Swedish population-based cohort study were employed. Nutrient density was calculated using the Sweden-adapted Nutrient Rich Foods 11.3 index. Dietary climate impact was calculated with data from life cycle assessments, including greenhouse gas emissions from primary production to industry gate. HRs and 95% CIs for MI and stroke were assessed with multivariable Cox proportional hazards regression, comparing a least-desirable diet scenario reference group (lower nutrient density, higher climate impact) with three diet groups that varied with respect to higher/lower nutrient density and higher/lower climate impact. Results Median follow-up time from the baseline study visit to MI or stroke diagnosis was 15.7 y for women and 12.8 y for men. The MI hazard was significantly higher for the men with diets of lower nutrient density and lower climate impact (HR: 1.19; 95% CI: 1.06, 1.33; P = 0.004), compared with the reference group. No significant association with MI was observed for any of the diet groups of women. No significant association with stroke was observed among any of the diet groups of women or men. Conclusions The results among men suggest some adverse health effects for men when diet quality is not considered in the pursuit of more climate-sustainable diets. For women, no significant associations were detected. The mechanism underlying this association for men needs further investigation.