The two names knocked Oliver and Olivia from the top spots for the two most common names given to babies born in England and Wales last year.
More than 7,500 boys and 5,000 girls were given the names last year.
Harry was the most popular boy's name for seven regions in England, and Amelia was the most liked girl's name in both the East and West Midlands.
An ONS spokesperson said they were unsure whether Harry was inspired by Harry Potter, Prince Harry, or course long-locked Harry from (scream!) One Direction - the boy band that found fame on the X Factor.
In the girls' corner, Bella, Willow, Elsie, Kayla, Francesca and Lydia all made the top 100 for the first time.
The top 10 names for girls and boys in 2011 were: