Guillermo is a distinctive boys' name in United States, ranking #752 in 2018 with 314 recorded births. The name reached its all-time peak in 1998 with 693 births ranking #369. Since 1996, the popularity has decreased by 54.6%. In 2018, approximately 1 in every 5,782 boys born was named Guillermo. STABLE Recent data shows the name is currently stable.