Breastfeeding is associated with medical and developmental benefits. This study aimed to assess associations between nutritional patterns in the first year of life and the likelihood of autism spectrum disorder (ASD). 270 children diagnosed with ASD (cases) and 500 neurotypical children (controls) matched to cases by sex, ethnicity, and birth date (± 3 months) were included in this retrospective case–control study. Both groups were ascertained from children born between 2014 and 2017 whose development/nutrition were monitored at mother–child health clinics in southern Israel. Conditional logistic regression was used to determine the independent association of nutritional patterns with ASD while adjusting for socio‐demographic and clinical characteristics. Both exclusive and partial breastfeeding modes were associated with decreased odds of ASD diagnosis (aOR = 0.221, 95%CI = 0.136–0.360; aOR = 0.494, 95%CI = 0.328–0.743, respectively). A breastfeeding duration of >12 months was associated with lower ASD odds (aOR = 0.418, 95%CI = 0.204–0.855), while the introduction of solids after 6 months of age was associated with higher ASD odds than the introduction of solids at 6 months (aOR = 2.455, 95%CI = 1.116–4.201). These findings suggest that a longer period of exclusive breastfeeding is associated with a subsequent reduced likelihood of ASD diagnosis, thus reiterating the importance of proper post‐natal nutrition for infant neurodevelopment.