It was the first multi-party vote in 40 years and the vote was aimed at ending a long civil war, with 32 candidates contesting the presidency.
Voters walked through former war zones to cast ballots for the first time in their lives, saying it was their only hope for an end to the fighting.
More than 25 million voters were protected by the biggest United Nations peacekeeping operation in the world.
They cast their ballots as police patrolled the streets and UN peacekeepers were stationed in strategic points.
Polling stations closed at 7:00 pm local time and counting began immediately.
Voters high hopes
"We often spent the night hiding in the bushes. The children don't go to school. It is not a good life," said Bienfait Mashagiro after voting in the northern town of Buganza.
"We are waiting for the new president to bring us peace."
"The people were worn out by this war. There was no way to make money, no schools," said Dieudonne Baroki, a teacher in the eastern town of Rutshuru near the troubled Rwandan border.
"I trust Kabila because he has tried to bring peace to all the country.... I think he will take the first round."
Most voters showed goodwill as they turned up at voting stations at daybreak, stood in queues and grappled with hundreds of names on huge ballots.
"This is truly a cause for much joy. I've never voted in my whole life," said Jerome Amza, 45.
But in the central diamond capital of Mbuji-Mayi, the stronghold of an opposition leader, Etienne Tshisekedi, some voters boycotted the election.
Three people were injured after youths torched a voting station.
Eleven other offices were attacked in the Kasai region, but the United Nations said the vote was overwhelmingly peaceful.
"Even if there were problems here and there, there has been a massive turnout in Kinshasa and the rest of the country. It is a success for the Congolese people," UN envoy Ross Mountain said.
Few strong rivals
The results of the presidential race are expected in three weeks.
Joseph Kabila was clearly leading in one voting district in the DRC's second city, Lubumbashi.
Out of 455 ballots counted in three hours, 343 had been cast in his favour, officials said.
The former soldier came to power in 2001 after his father Laurent was assassinated at the height of a five-year war that drew in seven armies and claimed four million lives, mostly through disease and neglect.
Kabila has won the support of the West, despite reservations about his business dealings.
The only strong rival for the presidency is Jean-Pierre Bemba, a wealthy former rebel leader who became vice president during the three-year transition period that followed the official end to the war in 2003.
The United Nations has called on the DR Congolese to accept the outcome of the vote, the first multi-party ballot since independence from Belgium in 1960, amid fears that the losers will take up arms.