The vote followed the barring of 9,000 mostly reformist and moderate candidates. Authorities said there was large fall in turnout compared to 2016.
Hardliners loyal to Iran's supreme leader looked set to sweep to a parliamentary election victory on Friday, likely cementing their grip on power.
Iranians voted in parliamentary elections that were seen as unlikely to change approaches to domestic or foreign policy.
Thousands of mostly moderate and reformist candidates were barred from the contest. The disqualification of those potential candidates, along with weariness over social restrictions and economic woes, were cited as a reasons for the low voter turnout.
Iranian authorities suggested a turnout of about 50%, compared to 62% and 66% respectively in the 2016 and 2012 elections.
'Hardly any voters'
Earlier in the day, DW's Theresa Tropper was at a polling station in northern Tehran Friday morning and reported "hardly any voters."
"With half of the candidates barred from running, people feel they don't have a choice this time and can't make a difference anyway," she said.
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Iran's Supreme Leader Ayatollah Ali Khamenei kicked off the voting process by casting the first ballot in Tehran on state television. In the broadcast, Khameini said voting is a "religious duty" and urged Iranians to vote as soon as possible.
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With Iran facing increasing discontent at home over economic hardships partially spurred by US sanctions, as well as growing isolation regarding diplomatic relations, analysts have said the voter turnout is expected to be a sign of Iranian citizens' support of their current government.
"I don't expect anything," a shopper at a market in northern Tehran told DW. "Nothing from the parliament and nothing from the president. If they really represented the people they would have long since done something, but all they do is talk."
Voting is set to run until Friday evening, with about 58 million Iranians eligible to vote for the representatives in the 290-member parliament.
jsi, lc/aw (Reuters, AFP, AP)