The decision dealt the biggest blow since World War Two to the European project of forging greater unity.
Global financial markets plunged on Friday losing about $2 trillion in value, while the British Pound suffered a record one-day plunge to a 31-year low.
The stunning Brexit vote drew mixed reactions from world leaders.
US President Barack Obama issued a statement saying, "The people of the United Kingdom have spoken, and we respect their decision.
"The United Kingdom and the European Union will remain indispensable partners of the United States even as they begin negotiating their ongoing relationship to ensure continued stability, security, and prosperity for Europe, Great Britain and Northern Ireland, and the world."
— The White House (@WhiteHouse) June 24, 2016
German Chancellor Angela Merkel voiced "great regret" at the British decision to leave the EU and called it a watershed for European unification.
She said the European Union is strong enough to find the "right answers" to Britain's vote to leave the bloc.
Italy's Prime Minister Matteo Renzi called upon the European Union to change direction following Britain's vote to leave the bloc.
"We have to change it to make it more human and more just, but Europe is our home, it's our future," Renzi said in a tweet.
— Matteo Renzi (@matteorenzi) June 24, 2016
Spain's acting Prime Minister Mariano Rajoy said the European Union should be reformed to focus on economic growth, jobs and greater integration after Britain's vote to leave the bloc.
He also said whatever was the result of Sunday's Spanish national election, the country would remain committed to the European project.
Russian President Vladimir Putin, speaking to reporters on a visit to Uzbekistan, said the outcome of the referendum reflected Britain's unhappiness with migration and security worries as well as dissatisfaction with the EU bureaucracy.
Brexit will have both positive and negative consequences for Russia and the world but the situation will correct itself in the near future, Putin said, adding that Russia would adjust its economic policy if necessary.
Putin also rejected British Prime Minister David Cameron's remarks that he would welcome Brexit as groundless and said that Russia did not influence Britain's vote to leave the European Union.
Turkish Prime Minister Binali Yildirim said that by opting to leave the European Union, British voters had expressed their disapproval of the negative campaign conducted against Turkey in the lead-up to the referendum.
In his first public statement following the United Kingdom's EU referendum, Yildirim rebuked British Prime Minister David Cameron for speaking out against Turkey's EU membership.
"Despite centering his campaign on Turkey, despite making several outlandish comments, British voters dismissed his claims and have informed Mr. Cameron that his views regarding Turkey were wrong."
Justin Trudeau, Prime Minister of Canada said in a statement, "The people of the UK have chosen to leave the EU.
"The UK and the EU are important strategic partners for Canada with whom we enjoy deep historical ties and common values. We will continue to build relations with both parties as they forge a new relationship."
Please read my statement on the results of the Brexit referendum:https://t.co/EDKgeHLOfJ
— Justin Trudeau (@JustinTrudeau) June 24, 2016
President of South Africa Jacob Zuma issued a statement saying, "It will take two years for the institutional changes that this vote implies to be negotiated and we remain committed to retaining strong trade and financial relations with both Britain and the European Union."
"The uncertainty that arises from this vote means that the volatility that has characterised capital markets in the lead-up to the vote may persist."
Japanese Prime Minister Shinzo Abe told reporters, "As G7 host, Japan will strive to stabilise financial markets and global economic growth. We need to respond firmly (to Brexit). What is needed is international cooperation."
Hungarian Prime Minister Viktor Orban said that Britain's vote to leave the European Union shows that Brussels must listen to the voice of the people and give proper answers to such pivotal issues as migration.
Orban said British people were not satisfied with the policies that the EU took on the migration crisis.