However, the Republican Referendum Commission, Slovak diplomat Frantisek Lipka, cautioned that returns from 45 polling stations, representing some 25,000 voters, still remain to be counted, and the results could change.
That figure, if confirmed in the final count, means that Montenegro has voted to end its three-year union with Serbia and become an independent country.
Montenegrin Prime Minister Milo Djukanovic has already claimed victory for the pro-independence camp, and supporters have been celebrating in Podgorica.
But the leader of the "No" campaign, Predrag Bulatovic, has refused to concede defeat.
Voter turnout in the independence referendum was a record 86.3 percent of the 485,000 eligible voters.
According to the referendum law, agreed with the European Union, the minimum "Yes" vote must be 55 percent for Montenegro to declare independence.
Croatian President Stipe Mesic has already sent a message of congratulations to Montenegro on its vote for independence. Mesic is the first foreign head of state to react officially to the vote.
The EU's foreign policy chief, Javier Solana, has congratulated Montenegro on a "successful referendum" and said the turnout of over 86 percent "confirms the legitimacy of the process." The European Union will, he said, "fully respect" the final result.
(compiled from agency reports)