"Ilham Aliyev has won," Ali Akhmedov, executive secretary of the New Azerbaijan Party led by Aliyev, told a rally in Baku.
"His victory is the victory of the Azeri people."
But Isa Gambar, the leader of the main opposition Musavat party, accused Azeri authorities of trying to "force people to vote" through curbs on democracy and media freedom which, he said, made participation pointless.
"It's a farce, a tragicomedy," Gambar said.
The names of six other candidates appeared alongside Aliyev on the ballot, but all were loyal to the authorities and some had not even bothered to campaign.
An exit poll by the local Rey (Opinion) polling firm earlier gave Aliyev 80.5 per cent of the vote, with his nearest rival, Gulamhussein Alibayli, getting just 5.4 per cent.
Another poll by the local ELS Independent Research Centre, gave Aliyev 82.6 per cent of the poll.
Shortly after polls closed at 7pm (1400 GMT), hundreds of the president's jubilant supporters streamed into the streets to celebrate, while cars flying Azeri flags and bearing portraits of the president clogged traffic in the capital.
Sona Azimova, a pensioner in Baku, said she voted for "our dear president" because he "is the only one who helps and thinks about the people".
"Look how our country is flourishing," she said.
Azerbaijan has one of the fastest-growing economies in the world.
Despite widespread corruption, the country's economy grew by 26 per cent last year, fuelled by energy exports.
The strategic, oil-rich country has been seen as a nation struggling to balance ties with the US and Russia, as Moscow and Washington vie for its allegiance.
The president is the son of Heydar Aliyev, the Caspian state's previous president, who dominated political life in the country for more than 30 years.
Despite criticism of his democratic record, Washington considers Aliyev as a key energy partner as Azerbaijan is the starting point for a strategic corridor of pipelines delivering oil and gas from the Caspian Sea to Turkey and on to Western markets.