And two-thirds of girls say they have experienced unwanted sexual attention in public, it adds.
The figures come from a report by children’s charity Plan International UK, which said many girls feel street harassment is “all part of growing up”.
It is calling on bystanders to challenge harassment when they see it.
The charity commissioned an opinion poll by Opinium of 1,000 teenagers and young women aged 14 to 21 across the UK in June 2018, and also carried out interviews with girls and academics.
66% of girls in the UK said they had experienced unwanted sexual attention or sexual or physical contact in a public place
35% of girls reported receiving unwanted sexual contact such as being touched, groped or grabbed
Girls as young as eight years old described witnessing or experiencing harassment
More than one in three girls received unwanted sexual attention such as being groped, stared at, catcalled and wolf-whistled while wearing school uniform
One-quarter of girls said they had been filmed or photographed by a stranger without permission