Around 44 million registered voters, out of a population of almost 100 million, are set to elect a president on December 20.
They will also choose between tens of thousands of candidates for legislative and local bodies in a country with vast natural resources but endemic conflict and corruption.
A "pre-campaign" has been underway for a while, with President Felix Tshisekedi, who is seeking a second term, attending several public events while his allies vaunt his record.
With the start of the official campaign, big rallies, media interviews, giant posters and handing out flyers will be allowed.
On opening day, Tshisekedi held a rally at the Martyrs stadium in Kinshasa, which was filled to its capacity of 80,000 people despite steady rain.
"He tells the truth, and he's the only one who is starting to do things," said Papa Kalombo, a Kinshasa official for the Union for Democracy and Social Progress (UDPS), which backs the incumbent.
One of Tshisekedi's main challengers, Martin Fayulu, who claims he was robbed of victory in 2018, addressed a rally in a nearby province.
"The time has come to transform Congo," Fayulu told the crowd.
In total there were a record 25,832 candidates for the legislative elections, 44,110 for provincial bodies and 31,234 for municipal councils, according to the Electoral Commission (CENI).
Violence in the east
The CENI faces the struggle of organising voting across a country of 2.3 million square kilometers(890,000 square miles) and limited infrastructure.
"There is a political will to stick to the electoral calendar, but there are doubts about the technical feasibility," said Tresor Kibangula, a political analyst at the Ebuteli research institute.
But for Sylvain Lesoye, a priest in a Kinshasa suburb, "the CENI is not inspiring confidence," citing the poor quality of many voter registration cards, some with illegible photos or signatures.
"The CENI knows the challenge it faces, and that its credibility is at stake," said political analyst Jean-Luc Kong. "But what really scares people is the crisis in the east."
The east of the country has been racked by fighting for three decades, and violence is surging again after the M23 group, allegedly supported by Rwanda, recently occupied much of North Kivu province.
Several Western countries, including the United States and France, have concluded that Rwanda backs the M23, though Kigali denies the claim.
The fighting is likely to impede normal voting in two territories in the province, but the whole process would be threatened if rebels take the provincial capital Goma.
"M23 will not take Goma," Tshisekedi has insisted, saying a return to calm is his priority along with improving services and the economy, building roads and respecting freedom of speech and of the press.
His record is mixed, according to analysts, and disastrous according to the opposition, which is already warning of widespread voting fraud.
'Wasting my time'
In addition to Fayulu, the main opposition candidates are Moise Katumbi, former governor of the Katanga mining region; Doctor Denis Mukwege, who received the Nobel Peace Prize in 2018 for his work with victims of sexual violence; and a former prime minister.
The incumbent president is favored to win, particularly since there is only one round of voting, but representatives of five leading opposition groups met this week in South Africa to study the possibility of proposing a single candidate.
A coalition has been formed and a common platform adopted, but Fayulu has yet to adhere.
In the wake of those talks, former premier Augustin Matata Ponyo dropped his presidential bid on Sunday in favor of Katumbi.
"Urgency dictates a single opposition candidate," Matata said in a Facebook message, accusing the government of preparing "massive electoral fraud."
Voters are mixed about the value of voting.
Eunice, a 20-year-old geography student, said she was "happy" to be voting for the first time.
But Ezechiel, a 24-year-old studying management IT, is discouraged. "There will be fraud, like in 2018," he said. "I am not going to waste my time."
Forum