Guillermo is a moderately popular boys' name in United States, ranking #382 in 1997 with 632 recorded births. This places Guillermo in the top 4% of ranked US boys' names for the year. Its actual usage is classified as Moderately Popular. The name reached its all-time peak in 1998 with 693 births ranking #369. In 1997, approximately 1 in every 2,983 boys born was named Guillermo. STABLE Recent data shows the name is currently stable.