Millie is a moderately popular girls' name in United States, ranking #174 in 2021 with 1,695 recorded births. The name reached its all-time peak in 2024 with 2,910 births ranking #86. Since 1996, the popularity has increased by 4,885.3%. In 2021, approximately 1 in every 967 girls born was named Millie. RISING Recent data shows the name is currently rising.