Preliminary results indicate former Prime Minister Milo Djukanovic has won more than 50 percent of the vote, thus avoiding a run-off. The pro-European leader defied Russia last year by taking the Balkan state into NATO.
With 80 percent of ballots counted, the Center for Monitoring and Research said on Sunday that Djukanovic had won about 53 percent of the vote, ahead of his main opponent Mladen Bojanic with 34 percent.
Djukanovic's Democratic Party of Socialists (DPS) declared him the winner on Sunday evening. Parliamentary party leader Milos Nikolic said at the party's headquarters: "Djukanovic is the new president of Montenegro... there will be no second round."
Sunday's vote was seen as test for the long-time leader, who favors European integration over closer ties to Montenegro's traditional ally, Moscow.
If confirmed, the result is approbation for his move last year to defy Moscow and take Montenegro into the North Atlantic Treaty Organization (NATO).
The former prime minister and his DPS have ruled the country for nearly 30 years. Current President Filip Vujanovic did not run due to term limits.
Montenegro's presidency is a ceremonial post, but is expected to become the real seat of power in the country if 56-year-old Djukanovic is confirmed as the winner.
The ballot is the first election in Montenegro since Djukanovic's party ignored calls from Russia and joined NATO in December last year. Montenegro is also one of the favourites to be the next country to join the European Union.
West versus Russia
Djukanovic is the best-known candidate in the race, with his campaign slogan declaring him a "leader, statesman and president of all citizens."
The six-time former prime minister said he was running for the presidency in order to stabilize Montenegro's pro-Western path amid regional and global instability and "defend" it from Moscow's influence.
Read more: The western Balkans: A region of secessions
The opposition says Djukanovic has ties to the mafia, an accusation he has denied.
Mladen Bojanic was Djukanovic's main rival, having been put forward by the leading opposition party, the Democratic Front, which prefers closer ties to Russia and accuses Djukanovic of both nepotism and corruption.
Djukanovic has pared back his anti-Russian rhetoric saying he wanted "normal relations with Russia if it is prepared to do the same," but he has also said he wants the country to "remain on its road of development," which would be better achieved through ties with Brussels.
Voters focus on employment
But for the 620,000 people in Montenegro, their votes may have been swayed by what work prospects are offered by the candidates rather than ties to the West or Russia. The average salary in Montenegro sits at around €500 ($615) and unemployment is more than 20 percent.
The country has also been marred by organized crime, with about 20 people killed by assassinations or car bombs over the last two years.
jm,law/tj (AFP, AP, dpa)