The study by U.K.-based children's charity, Plan International, interviewed 301 teenage girls and boys in Colombia, Uganda and Spain, about gender roles and stereotypes.
"The horrifying testimonies of girls reveal that almost every single experience for them – be it at home, school, in public transport, or on social media – is a reminder that they are judged to be inferior to boys," said Anne-Birgitte Albrectsen, head of Plan International.
"Violence in particular has become so normalised that it is seen by many as an accepted part of being female," she said in a statement.
A third of all women experience physical or sexual violence at some point in their lives. An estimated one in five will be a victim of rape or attempted rape, says the United Nations, and high rates of femicide and domestic abuse grip many countries.
The Plan International study found gender discrimination starts in the home, where expectations about girls' behaviour are reinforced by their parents, brothers and the wider family.
Girls are responsible for most of the domestic chores and caring activities, while violence, including sexual violence, is condoned.
"I think the village people have strong desire for young girls. Raping young girls is not (a challenge) for them," 17-year-old Kisakye from Uganda is quoted as saying in the report.
The study attributed gender inequality to traditional misogynist attitudes that view girls inferior and less capable than boys in all the three countries where research was done.
"This deep-seated bias which views women and girls as inferior is the greatest barrier to ending inequality," the report said.
"The key to equality is to challenge the widespread perception that girls are worth less than boys," it said.
Too often girls have little or no say about when and with whom they get married or whether they go to school.
Girls' bodies and sexuality are treated as "commodities to be bartered," the report said.
In Uganda, poverty can force girls into transactional sex with older boyfriends who provide money for basic things from sanitary pads to school fees so they can stay in class, it said.
However, the study found that in Uganda and Colombia girls no longer see themselves as solely responsible for promoting gender equality.
Increasingly they are seeking "allies", like community leaders, mayors, teachers and boys to change social norms.
"This is a clear change from evidence collected in earlier research when bringing about change was seen as very much the responsibility of girls and their mothers," the report said.