Iron deficiency (ID) is a widespread nutritional deficiency that has the potential to impair a child’s growth and development. There is evidence linking infant feeding practices to this health issue, but there is limited research on whether ID and these feeding practices are prevalent across a range of ethnic groups. To evaluate the association between maternal ethnicity and ID in early childhood, and to evaluate whether infant feeding practices linked to ID differ across ethnic groups. This was a cross-sectional study of healthy children 1 to 3 years of age, recruited during scheduled health supervision visits between September 2008 and July 2017 from 9 primary care practices. Adjusted odds ratios (OR) were estimated using logistic regression adjusted for age, sex, body mass index, maternal education, family income, breastfeeding duration, daily cow’s milk intake, prolonged bottle use, infant formula use, and C-reactive protein to evaluate the association between maternal ethnicity and ID (serum ferritin <12 µg/L). Chi-square analyses were conducted to describe infant feeding practices (breastfeeding duration beyond 12 months of age, cow’s milk consumption >500mL per day, bottle feeding beyond 15 months of age, low meat consumption and infant formula use) across maternal ethnic groups. Of 1851 children included in the analysis, 12.2% of children had ID. There was an increased odds of ID among children of South Asian (OR=1.72; 95% confidence interval (CI) 1.07, 2.77; P=0.02) and West Asian/North African (OR=2.40; 95% CI 1.04, 5.58; P=0.04) maternal ethnicities, and a decreased odds of ID among children of East Asian maternal ethnicity (OR =0.37; 95% CI 0.15, 0.94; P=0.04) compared with children from the European referent group. Compared with the European referent group, a significantly higher proportion of South Asian children were bottle feeding beyond 15 months (44% vs. 26%), and had lower meat consumption (88% vs. 97%). Compared with the European group, a significantly higher proportion of West Asian/North African (28% vs. 13%) and African & Caribbean (25% vs. 13%) children had higher infant formula use. In this study, we found an increased odds of ID among children of South Asian and West Asian/North African maternal ethnicities, and that a high proportion of children of South Asian, West Asian/North African and African & Caribbean maternal ethnicity had feeding practices linked with ID. Culturally-tailored approaches to educating parents on healthy infant feeding practices may be an important strategy in preventing ID in young children.