The report comes less than a week before the country's first democratic elections in more than 40 years, which UNICEF ambassador Martin Bell said could offer some hope to the country's child victims.
"These elections may be the opportunity of their lifetime," said Bell, a former war correspondent who wrote "Child Alert: Democratic Republic of Congo."
"It is easy to be overwhelmed by what has happened," he said. "But we owe it to the children to give them the future they deserve."
The children are victimized by instability lingering from the wars of 1996-2002, when neighboring Rwanda's genocide spilled over its borders and a regional battle began largely over control of Congo's vast mineral resources, drawing in Burundi, Rwanda, Uganda, Zimbabwe, Namibia and Angola.
Soldiers and rebels continue to terrorize eastern Congo, forcing some 360,000 people from their homes this year despite the presence of some 17,500 U.N. peacekeepers.
"Constant migration robs (children) of schooling, health care and the chance for a normal life," the report says. "And they are caught up in combat as soldiers and camp-followers."
UNICEF estimates there are hundreds of thousands of victims of combatants using sexual violence as a weapon of war.
An estimated 1.1 million people live with the disease in the Congo — a number UNICEF says will climb as war, gang rape and community displacement continue to wrack the country.
The report also states that more children under the age of 5 die every year in Congo, population about 62 million, than in either China — a country with 23 times the population — or all of Latin America.
"Children bear the brunt of conflict, disease and death, but not only as casualties," said Tony Bloomberg, UNICEF representative for Congo. "They are also witnesses to, and sometimes forced participants in, atrocities and crimes that inflict physical and psychological harm."
Bloomberg and Bell said support must increase for schools, which UNICEF sees as a path for reintegrating child soldiers and molestation victims as young as 6 back into a stable community.
"A normalized school environment not only helps the child in terms of trauma, but it also gives them a tool for the future," Bloomberg said. "It gives them hope."
Congo's vote on Sunday is the biggest election the U.N. has helped organize. Besides the U.N. peacekeepers, a new European Union force of 1,000 soldiers is being deployed to maintain calm at 50,000 ballot stations, scattered across a country the size of Western Europe with only a few hundred miles of paved roads.
Thirty-three candidates are running for president and 9,000 for legislative seats. Many are asking to have the campaign suspended until cheating charges, which are backed by several human rights groups, are investigated.