Temporary expansion of the Child Tax Credit (CTC) during the COVID-19 pandemic provided additional monthly income for US families, with no restrictions on use, from July through December 2021. This study examined food security and children's dietary intake after three months of expanded CTC payments. Parents completed online surveys before and after three months of CTC payments. Among parents participating in the expansion, food and beverage purchases were the most common use of expanded CTC funds (45.9 percent), particularly in households with very low food security (63.0 percent). From before to midway through the CTC expansion, very low food security decreased from 12.7 percent to 5.6 percent, and simultaneously, food security increased from 57.4 percent to 66.4 percent. The CTC expansion was also associated with decreases in children's consumption of added sugar, sugar-sweetened beverages, and sweetened fruit beverages. No changes were observed in children's intake of other dietary components. Our findings suggest that the expanded CTC payments may have helped lessen food insecurity and supported reductions in children's intake of added sugar in participating households.