Guillermo is a distinctive boys' name in United States, ranking #755 in 2016 with 322 recorded births. The name reached its all-time peak in 1998 with 693 births ranking #369. Since 1996, the popularity has decreased by 53.5%. In 2016, approximately 1 in every 5,892 boys born was named Guillermo. STABLE Recent data shows the name is currently stable.