In 2019, a globally sustainable dietary pattern that primarily emphasizes the consumption of plant-based foods was proposed by the EAT-Lancet Commission. However, there is limited evidence regarding the association of this diet with coronary events. To determine the association between the EAT-Lancet Reference Diet (ELD) and premature coronary artery disease (PCAD) risk and its severity. This multi-center, case-control study was conducted within the framework of the Iran premature coronary artery disease (I-PAD). A total of 3185 participants aged under 70 years in women and 60 years in men were included. Cases were those whose coronary angiography showed stenosis ≥ 75% in at least one vessel or ≥ 50% in the left main artery (n = 2033), while the controls had normal angiography results (n = 1152). Dietary intake was assessed using a validated food frequency questionnaire. Logistic regression was utilized to examine the association between ELD and presence of PCAD. Compared with individuals in the first quartile, those in the highest quartile of ELD (OR = 0.29, 95% CI: 0.21, 0.39; P for trend < 0.001) and ELD calculated with minimum intake (OR = 0.39, 95% CI: 0.29, 0.52; P < 0.001) had lower risk of PCAD. Individuals in the highest quartile of adherence to the ELD and ELD with minimum intake had 78% and 72% lower risk of having severe PCAD compared with those in the lowest quartile, respectively. An inverse association was observed between adherence to the ELD and PCAD risk and its severity. Large-scale prospective cohort studies are required to confirm these findings.