Postpartum maternal diet quality has been linked with optimal infant feeding practices. However, whether maternal diet quality during pregnancy influences infant feeding practices remains unclear. The present study explored the relationship between maternal diet quality in pregnancy and infant feeding practices in Australian women. A brief 15-item food frequency questionnaire was used to collect maternal dietary data (n = 469). Diet quality was calculated using a modified 2013 Dietary Guideline Index (DGI). Multivariable linear and logistic regressions with adjustment for covariates were used to examine associations between maternal diet quality in pregnancy and infant feeding practices: infant feeding mode, breastfeeding duration and timing of solids introduction. Higher DGI score during pregnancy was associated with higher odds of breastfeeding than formula/mixed feeding (adjusted OR 1.03, 95% CI 1.00, 1.07), longer breastfeeding duration (adjusted β 0.09, 95% CI 0.03, 0.15) and higher odds of breastfeeding for ≥6 months (AOR 1.04, 95% CI 1.02, 1.07) than for <6 months. Associations between maternal DGI score and breastfeeding variables were moderated by maternal country of birth, with significant associations observed in Australian-born mothers only. No association was found between maternal DGI score and timing of solids introduction. Higher maternal diet quality was associated with better infant feeding practices, and the association was moderated by country of birth. Our findings provide evidence to support the initiation of dietary interventions to promote diet quality during pregnancy, particularly among Australian-born women. Further research could explore underlying mechanisms linking maternal diet quality and infant feeding practices.