Voting on proposed constitutional changes have taken place at 120 polling stations in 57 countries since March 27, the YSK said in a statement sent to Anadolu Agency.
About 70,000 people voted at customs gates in Turkey and ballot boxes at the borders will remain open until April 16.
Approximately 2.9 million Turkish expatriates are eligible to vote on the referendum. The referendum is just the fourth opportunity expatriates have had to vote in Turkish elections.
Overseas turnout was 8 percent during the 2014 presidential election — the first time Turkish nationals were able to vote from abroad. By the November 2015 elections that figure had rose to 40 percent as a little more than 1 million Turks cast ballots
As of Sunday morning, more than 600,000 Turks in Germany, where the majority of the expats live, voted on the referendum while nearly 132,000 voters went to polls in France, according to the YSK.
In the U.S., nearly 35,000 people voted, according to unofficial figures, representing a 35 percent turnout -- higher than that of the Nov. 1, 2015 general elections.
In Kzakstan, 2,427 eligible voters went to polling stations, diplomatic sources told Anadolu Agency.
A total of 14,359 ballots were cast in Australia, 8,322 voters exercised their rights in Saudi Arabia, 711 in Georgia and 346 in South Africa's administrative capital of Pretoria.
With polling stations closed in Europe, votes will be transferred Monday to Turkey where they will be counted April 16.
The voting in Europe began amid a diplomatic standoff between Turkey and Germany after German authorities cited security concerns and banned rallies by Turkish ministers who favor a presidential system.
Several German politicians have also publicly campaigned against the proposed presidential system, drawing sharp criticism from the Turkish government and accusations of interfering in Turkey's internal affairs.
Tension also grew between Turkey and the Netherlands after Dutch authorities barred two Turkish ministers from addressing the expat community ahead of the referendum.
Turkish Foreign Minister Mevlut Cavusoglu was refused permission to land in Amsterdam and Family Minister Fatma Betul Sayan Kaya -- who had traveled to the Netherlands from neighboring Germany -- was forced to leave the country under police escort after she was blocked from entering the Turkish consulate in Rotterdam.
Leading politicians in Austria, Germany and the Netherlands proposed a ban on rallies by Turkish politicians across Europe.
Austrian authorities also prevented former Energy Minister Taner Yildiz and AK Party MPs from speaking due to "security concerns".
While European countries banned rallies in support of the “Yes” campaign, they allowed Turkish opposition figures who back a “No” vote to hold demonstrations without hindrance.
The April 16 referendum in Turkey addresses a host of constitutional reforms that would hand wide-ranging executive powers to the president.
The post of prime minister would be abolished and the president would also be allowed to retain ties to a political party.
Other changes include the minimum age of parliamentary candidates reduced to 18 and the number of deputies increased to 600.
Also, simultaneous parliamentary and presidential elections for a five-year term would be held in November 2019 under the new Constitution.