Polling stations across the country opened at 8:00 a.m. (0430 GMT) on Friday in the 11th parliamentary and Assembly of Experts elections and Leader of the Islamic Revolution Ayatollah Seyyed Ali Khamenei was among the first to cast his ballot.
Speaking after casting his vote, the Leader said, “These elections mark a day of national celebration and I have to congratulate all my fellow countrymen across the country on this occasion."
"Secondly, the day of elections is the day of the fulfillment of the civil rights of the people which seek to vote and participate in determining the future of the country, as they are entitled to," the Leader added.
"Thirdly, it is a religious obligation and the truth is that it is elections which guarantee the national interests of the country and anyone who is interested in the national interests of the country should vote," Ayatollah Khamenei said.
The Leader urged voters to turn out early in the day and to vote based on the number of total competing candidates in any given city.
Ayatollah Khamenei concluded his remarks by praying for the country and also thanking the media for covering the event.
Images shared on social media also showed long lines of people standing in front of polling stations waiting to cast their votes early in the morning.
Speaking after voting, Iranian President Hassan Rouhani said he "hoped that the best make it to the 11th parliament".
"What the people demand is a more active parliament which can better focus on resolving the problems which affect their lives," Rouhani added.
The Iranian president said since Iran's first parliamentary elections following the Islamic Revolution on March 1980, elections have been held regularly in the country despite times of hardship such as the 1980-88 Iraq war against Iran.
Rouhani added that the late founder of the Islamic Republic Imam Khomeini "always stressed the need for the elections to be held as scheduled."
He also said Iran's parliamentary elections have been held without any interruption of any sort in the last ten years, marking "a unique reality in the history of democracy and of Iran".
Iranian Foreign Minister Mohammad Javad Zarif said that "the people are the main backers of the Islamic Revolution," adding Iran's diplomacy is also dependent on the support of its people.
Zarif added that Iranians will not allow "someone sitting in Washington to decide for them, specifically someone who has the blood of General Soleimani on his hands".
The region’s most popular anti-terror military figure, Lieutenant General Qassem Soleimani, was assassinated in early January by Washington while on an official visit to Iraq.
'Washington's disregard for democracy'
The voting comes a day after the US imposed sanctions on five senior members of Iran’s Guardian Council which is responsible for supervising the electoral process in the country.
US special representative for Iran Brian Hook - who announced the measures Thursday - accused the officials of preventing free and fair elections.
On Friday, Guardian Council spokesman Abbas Ali Kadkhodaei slammed the sanctions as "sham and illegitimate" measures demonstrating the United States' disregard for democracy.
He added that the US in fact "desired the region's dictatorial governments as child-killing regimes, seeing them as cows that can be milked for benefit".
In a tweet on Thursday, Ayatollah Mohammad Yazdi, one of the sanctioned Guardian Council officials, said that it was his "highest honor" to be sanctioned by "those whose hands were stained by the blood" of General Soleimani.
Speaking on Friday, Secretary of Iran's Guardian Council Ayatollah Ahmad Jannati mockingly quipped at the sanctions, saying that they demonstrated the "mind paralysis" of those which have imposed them on the Guardian Council members.
"Yes, they sanctioned us and I am now thinking what to do with all the money we have left in the US. We also can't go to the US for Christmas celebrations any longer," Ayatollah Jannati told reporters, who laughed in response.
The voting comes after a one-week election campaign, which officially kicked off last Thursday.
More than 7,000 candidates are competing to enter the parliament. A winning candidate must have at least 20 percent of the votes cast in their constituency in order to become lawmaker for a four-year term.
A total of 57,918,000 people are eligible to cast their ballots. There would be one lawmaker at Majlis per each 190,000-strong segment of the Iranian population.
Iranian Interior Minister Abdolreza Rahmani Fazli said Wednesday that a total of 55,000 polling stations and over 200 constituencies have been prepared across the country’s 31 provinces for the people to cast their votes.