Background: Cognitive development plays an important role in a child’s life. Cognitive development and sleep patterns can interfere with the brain cell growth related to health and nutrition in children. Many children are reported to have eating difficulty in infantile anorexia. Infantile anorexia is an eating disorder during the children’s period of learning (6 - 36 months of age). The disorder is characterized by extreme refusal of eating, deficiency of growth, and loss of typical appetite. Objectives: This study aimed to determine the association of infantile anorexia at 12 - 36 months of age with cognitive development and sleep patterns in children. Methods: This analytic observational study with a case-control design was conducted on the subjects divided into 40 infantile anorexia children and 40 controls. Infantile anorexia was diagnosed by a trained pediatrician. Cognitive assessment was measured by the Capute Scale test. The Brief Infant Sleep Questionnaire measured the data on children’s sleep patterns. The association of infantile anorexia and children’s cognitive development was analyzed by the chi-square test. Results: The result showed a significant association between infantile anorexia and children’s cognitive development (OR: 52.76; 95% CI: 6.58 - 423.0; P < 0.001). A similar association was also observed between children’s sleep patterns and infantile anorexia (OR: 4.88; 95% CI: 1.80 - 13.21; P < 0.002). Conclusions: The findings of this study demonstrated that children with infantile anorexia are more likely to have impaired cognitive development and abnormal sleep patterns.