Initiatives to promote children's nutrition and prevent childhood obesity are vital. Dietary patterns are a useful way to characterize whole diets, though no previous early childhood health promotion trial to our knowledge has assessed intervention impact using this approach. This research aimed to assess the effect of a healthy eating and physical activity intervention on young children's dietary patterns. The Melbourne Infant Feeding Activity and Nutrition Trial Program was a health promotion, cluster-randomized controlled trial involving 542 families. Child diets were assessed by multiple 24-h recalls postintervention at ~18 mo of age. An Obesity Protective Dietary Index (OPDI) was created and dietary patterns were also assessed by principal components analysis (PCA). These outcomes were used to compare intervention and control participants to test the effectiveness of the intervention. Children in the intervention arm scored higher (15.6 ± 5.9) than those in the control arm (14.5 ± 6.7) for the OPDI (scores out of 30, P = 0.01). Three dietary patterns were identified by PCA; however, the scores did not substantially differ between the intervention and control arms. In conclusion, this paper presents novel results in both the evaluation of an early childhood health promotion intervention and the assessment of child dietary patterns. The results highlight the capacity for such an initiative to improve child diets and the need for further research in this area.