Millie is a popular girls' name in United States, ranking #73 in 2025 with 3,353 recorded births. The name reached its all-time peak in 2025 with 3,353 births ranking #73. Since 1996, the popularity has increased by 9,761.8%. In 2025, approximately 1 in every 479 girls born was named Millie. RISING Recent data shows the name is currently rising.