Hague — flanked by Jolie and the U.N. special representative on sexual violence in conflict, Zanab Bangora — announced that G-8 ministers pledged $36 million in additional funding to fight sexual violence in conflict.
Calling the issue "the slave trade of our generation," Hague said the ministers also agreed to declare that rape and serious sexual violence in conflict constitute war crimes and grave breaches of the Geneva Conventions.
Jolie welcomed the "long overdue stand" on sexual violence, adding that the international political will to combat sexual violence has been "sorely lacking."
Sexual violence has been used as a weapon in several conflicts, including the civil war in Syria, the Bosnian war, and during fighting in the Democratic Republic of Congo.
On Syria, where the U.N. estimates that a two-year civil war has killed more than 70,000 people, U.S. Secretary of State John Kerry met with Syrian opposition leaders in London on Wednesday to discuss ways to step up nonlethal aid to the rebels.
But there was no mention of assisting the rebels in Thursday's G-8 statement, reflecting divided opinion among the nations, and in particular Russia, on how to address the Syria conflict.
The communique said ministers are "appalled" at the deaths in Syria and the fact that the war has forced more than a million refugees to flee to neighboring countries.
The ministers "reaffirmed their commitment" to supporting a political transition in Syria and condemned the ongoing use of heavy weapons against residential areas.
"The humanitarian situation in Syria is deplorable and continues to worsen," the communique said, urging greater humanitarian assistance and improved access to the Syrian people.
Britain and France have been pushing for the European Union to lift or amend its arms embargo on Syria so weapons can be sent to rebel fighters.
Hague said earlier this week that no decisions have been made on whether the U.K. will allow the embargo to expire as scheduled June 1, effectively clearing the way to arm the rebels. He said if the situation in Syria continues to deteriorate, there will be a "strong case" for amending or lifting the arms embargo.
AP reporter Martin Benedyk contributed to this report from London.