He said that the fact that such large percent of voters opted for him is a strong confirmation that Montenegro should continue along the path towards the EU.
Djukanovic is followed by opposition candidate Mladlen Bojanic, with 33.9% of votes.
Djukanovic thanked his coalition partners, noting that he expected a similar victory in the upcoming parliamentary election.
The opposition accuses Djukanovic of being linked to the mafia, which he denies.
Bojanic says his opponent "is the man holding Montenegro and its institutions hostage", and he says he'll "continue to fight to free Montenegro of Djukanovic and his dictatorship". "I am appealing to opposition voters not to view this as a defeat but as a basis for further struggle".
Djukanovic's Democratic Party of Socialists (DPS) declared him the victor on Sunday evening.
Kosovo leaders including President Hashim Thaci and Prime Minister Ramush Haradinaj have congratulated Djukanovic on the victory. "This is a great victory, a historic victory".
The results were a major boost for Djukanovic, who defied Russian Federation to take his country into North Atlantic Treaty Organisation a year ago.More news: Putin Dampens Tensions, as US, French, UK Strike on Syria Looms
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Djukanovic, who has previously served as president and prime minister, faced off several other candidates.
The independent NGO Centre for Monitoring (CEMI) said the six-time former prime minister had garnered 53.5 percent of the vote with two thirds of ballots counted.
If confirmed, the result will present a major boost for Djukanovic, who defied Russian Federation to take his country into North Atlantic Treaty Organisation a year ago.
Political heavyweight Milo Djukanovic took a strong lead in Montenegro's presidential election on Sunday, according to preliminary results.
Because the military alliance was joined by Montenegro in December, the vote Sunday is your initial. It's seen as a test for Djukanovic, who favors European integration over closer ties to traditional ally Moscow.
Djukanovic, a former prime minister and the country's dominant politician, and the Democratic Party of Socialists have ruled Montenegro for almost 30 years.
If the 56-year-old wins the presidency, now a ceremonial post held by his ally Filip Vujanovic, it is expected to become the real seat of power in the country of 620,000 people.
Sunday's vote passed off peacefully amid fears of disorder after 20 people were arrested and accused of trying to stage a coup during legislative elections in 2016.