Io is a distinctive boys' name in United States, ranking #11217 in 2015 with 6 recorded births. This places Io in the bottom 20% of ranked US boys' names for the year. Its actual usage is classified as Rare. The name reached its all-time peak in 2014 with 7 births ranking #10041. In 2015, approximately 1 in every 319,376 boys born was named Io. FALLING Recent data shows the name is currently falling.