Guillermo is a distinctive boys' name in United States, ranking #795 in 2017 with 289 recorded births. The name reached its all-time peak in 1998 with 693 births ranking #369. Since 1996, the popularity has decreased by 58.2%. In 2017, approximately 1 in every 6,402 boys born was named Guillermo. STABLE Recent data shows the name is currently stable.