2014 "was marked by harrowing accounts of rape, sexual slavery and forced marriage being used by extremist groups, including as a tactic of terror," Secretary General Ban Ki-moon said in the report.
The review found that sexual attacks in Iraq, Syria and Nigeria were not incidental, but "integrally linked to strategic objectives, ideology and funding of extremist groups."
Rape and other forms of sexual violence are being used to advance recruitment, terrorize populations, displace communities and generate revenue through sex trafficking, the slave trade and ransom.
Islamic State (IS) and Boko Haram were among 13 groups added to a UN list of parties that resort to sexual violence - a measure intended to focus greater international attention on those conflicts.
In all, 45 groups are listed including 12 rebel factions from the Democratic Republic of Congo and five groups from South Sudan, including the national police service.
Alarm over Chibok girls
Signup to our newsletter and follow us on Facebook and Twitter!
The report was released on the eve of the anniversary of the kidnapping of more than 200 girls from Chibok in northern Nigeria by Boko Haram, described as "one of the most alarming episodes of 2014."
"Forced marriage, enslavement and the 'sale' of kidnapped women and girls are central to Boko Haram's modus operandi and ideology," said the report.
In Iraq, the IS seizure of Mosul in June led to reports of sexual slavery of young women, particularly from the Yazidi minority, sold as slaves in open markets or given to IS fighters as gifts, the report said.
Over recent months, some 1,500 civilians may have been forced into sexual slavery in Iraq, the report said.
The report noted a "significant increase" in the number of cases of sexual violence in Syria with abductees from Iraq being sold in markets in IS-controlled areas of Syria.
It cited allegations of a mass rape in the Darfur town of Tabit by Sudanese armed forces in late October, even though the United Nations has said it has been unable to verify those claims.
The report covered 19 countries and detailed sexual violence in countries including the Democratic Republic of Congo, Somalia, South Sudan, Sudan and the Central African Republic, as well as Syria and Iraq.
The Security Council will look at ways of addressing sexual violence in conflict based on the findings of the report during an open debate on Wednesday.