Fionna is a distinctive girls' name in United States, ranking #5208 in 1998 with 20 recorded births. The name reached its all-time peak in 2012 with 41 births ranking #3804. Since 1996, the popularity has increased by 66.7%. In 1998, approximately 1 in every 88,344 girls born was named Fionna. FALLING Recent data shows the name is currently falling.