The Special Supplemental Nutrition Program for Women, Infants and Children (WIC) required major revisions to food packages in 2009. This study examines associations between WIC revisions and nutritional profiles of packaged food purchases from 2008 to 2014 among 4,537 low-income households with preschoolers in the U.S. using Nielsen Homescan Consumer Panel data. Among WIC households, significant decreases in purchases of calories (−11%), sodium (−12%), total fat (−10%), and sugar (−15%) occurred, alongside decreases in purchases of refined grains, grain-based desserts, higher-fat milks, and sugar-sweetened beverages, and increases in purchases of fruits/vegetables with no added sugar/fats/salt. Income-eligible nonparticipating households had similar, but less pronounced, reductions. Overall, WIC food package revisions may encourage WIC families to make healthier choices among their overall packaged food purchases.