Voting will close at 6pm local time (15:00 GMT) on Tuesday and there will be no extensions.
Approximately 21 million Iraqis are eligible to vote for the 329-seat parliament, which will elect the president and give confidence to the incoming government.
On Sunday, members of the Iraqi security forces and internally displaced persons headed to polling stations to vote early.
Election officials said results are expected to be known within 24 hours after voting closes and will be formally approved once all appeals have been reviewed.
Prime Minister Mohammed Shia al-Sudani said the elections were held in a “safe and stable atmosphere” and praised security forces for maintaining order.
“The election confirms the principle of a peaceful transfer of power, and the government is paying great attention to it,” he told reporters after the vote in Baghdad.
He stressed that the elections were held on Constitution Day in the presence of international observers “to present a clear picture of the electoral process.”
Al-Sudani, who will be elected in 2022, is seeking re-election for a second term and is expected to win a significant number of seats.
The current parliament, dominated by Shiite parties and blocs, is scheduled to begin its term on January 9, 2022 and end on January 8, 2026.
By law, Iraq must hold parliamentary elections at least 45 days before the end of the parliamentary term.
The next prime minister will be voted in by whichever coalition can negotiate with allies to become the largest parliamentary bloc.
Iraq’s three branches of government have traditionally been sectarian: the president is Kurdish, the prime minister is Shia, and the speaker of parliament is Sunni, ensuring that all strata of society are represented in government.
MNA/Press TV