Rhiannon is a moderately popular girls' name in United States, ranking #467 in 1998 with 554 recorded births. The name reached its all-time peak in 1999 with 651 births ranking #424. Since 1996, the popularity has increased by 86.5%. In 1998, approximately 1 in every 3,189 girls born was named Rhiannon. STABLE Recent data shows the name is currently stable.