Every year, one billion girls and boys experience violence and the economic costs alone are estimated at six trillion euros a year.
Between January 2011 and March 2017, the EU says it has supported children's rights through its external relations with over €8bn in 142 developing countries.
Almost 10 per cent of this was directly dedicated to tackling child labour, trafficking of children, supporting children in armed conflicts, preventing harmful practices and sexual exploitation, as well as other violence-related projects.
At the campaign launch, the European Commissioner for international cooperation and development, Neven Mimica, was joined by Fatou and Samia, who come from Sénégal and Bangladesh.
"One of my classmates, aged 16, was given as child bride by her grandfather. He thought that would protect her from getting pregnant before marriage. She complained but her family abandoned her," said Fatou, from Sénégal.
"I am now engaging my local child protection committee to raise awareness of class mates, adults and local authorities."
Mimica said, "Violence against girls is one of the greatest injustices of our time, which crosses all borders, generations, nationalities and communities. We need to join forces with girls all across the globe to end this violence for good."
He went on, "Building on our strong record of investing in girls, we are currently working together with the United Nations on a ground-breaking initiative to eliminate all forms of violence against women and girls around the world."
This, he said, would be officially launched in September.
The campaign is called 'It takes a world to end violence against children' and the Commissioner said that "creating a world free of violence against children is beyond the reach of any one institution or organisation."
The aim, therefore, is to bring together different actors to "strengthen political will and accelerate progress to end violence against children."
The Commissioner said the campaign will be supported by "very substantial, dedicated funding, and make sure that throughout girls' faces are visible and their voices heard."
He added, "Joining forces with girls to end violence isn't just 'nice to have.' It's an essential first step in ensuring that every girl has the opportunity to fulfil her true potential."
The campaign is backed by the Global Partnership to End Violence Against Children and civil society representatives.
A recent report by the Global Partnership, 'Counting pennies', found that in 2015, of the total €152bn overseas development assistance, less than 0.6 per cent was allocated to ending violence against children.
Trihadi Saptoadi, who leads World Vision's programmes and policy internationally, said, "The stakes for ending violence against children could not be higher. If we don't end violence against children now, we risk jeopardising the progress and losing the investments made in child survival, health and education.
"The cost of inaction is far higher than the cost of investing in actions to end violence against girls and boys."
The new European Consensus on Development, which was agreed by the EU and member states earlier this year, makes gender equality a priority.
It recognises women and girls as "powerful agents of change and drivers of development, and not as victims or passive beneficiaries."
The Commission's Gender Action Plan sets out a practical framework to ensure women and girls' physical and psychological well-being, strengthen their voice and empower them economically.
A Commission spokesperson said, "Over the next five years, the campaign will seek to positively impact the lives of hundreds of millions of boys and girls vulnerable to violence making a significant contribution toward Sustainable Development Goals 5 and 16."
World Vision works in close to 100 countries in most regions of the world including Latin America and the Caribbean, Europe, Africa, the Middle East and the Asia Pacific Region.