Over the past 110 years, 11 974 girls have been named Rhiannon. The name Rhiannon ranks 1181th in the United States among the most common names for girls. For the first time more than ten times newborns were named Rhiannon in 1976. The peak of popularity of the name Rhiannon 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.