Millie is a moderately popular girls' name in United States, ranking #104 in 2023 with 2,562 recorded births. The name reached its all-time peak in 2025 with 3,353 births ranking #73. Since 1996, the popularity has increased by 7,435.3%. In 2023, approximately 1 in every 626 girls born was named Millie. RISING Recent data shows the name is currently rising.
Millie is a warm vintage short form that now often stands as a given name in its own right. Its exact traditional meaning depends on which longer name family sits behind it.
Its rise fits the broad return of nickname-style vintage names that feel affectionate and energetic. Millie works especially well because it is cheerful without feeling flimsy.