Guillermo is a distinctive boys' name in United States, ranking #850 in 2022 with 287 recorded births. The name reached its all-time peak in 1998 with 693 births ranking #369. Since 1996, the popularity has decreased by 58.5%. In 2022, approximately 1 in every 6,078 boys born was named Guillermo. STABLE Recent data shows the name is currently stable.