Over the past 110 years, 27 602 boys and 10 girls have been named Guillermo. The name Guillermo ranks 613th in the United States among the most common names for boys. For the first time more than ten times newborns were named Guillermo in 1910. The peak of popularity of the name Guillermo came in the 1990s and 2000s. You can see absolute numbers and relative numbers on the chart. Indicators per 100K more accurately assess the popularity of the name.