Top election official Ali Reza Afshar said turnout had been “glorious” and higher than in previous polls.
But observers had predicted turnout would not be much above 50%, perhaps lower in the capital, Tehran.
The BBC’s Jon Leyne in Tehran says the lack of choice among candidates could have discouraged voters.
Voting was extended by five hours so polling stations could cope with the large numbers, officials said.
But polling stations in Tehran were quiet, our correspondent says.
With the field narrowed thanks to the disqualification of reformist candidates, he says the only question is how seats will be shared out between competing conservatives.
The Iranian authorities had called for a big turnout to defy the US and other countries they say are Iran’s enemies.
The election will shape the political map ahead of 2009’s presidential poll.
President Mahmoud Ahmadinejad flew in from an Islamic summit in Senegal to cast his vote.
He said the world had chosen Iran as its “role model and saviour”.
Real winners
The reformists seem to have given up the fight after many of their candidates were disqualified on the grounds of alleged lack of loyalty to Islamic values, says our correspondent.
They made up the bulk of about 1,700 candidates barred from running by Iran’s Guardian Council – an unelected body of clerics and jurists that vets election candidates.
The Guardian Council has denied bias.
Analysts expect the poll’s real winners to be former members of the hardline Revolutionary Guards, who could replace the Muslim clergy as the biggest force in the assembly.
Supreme Leader Ayatollah Ali Khamenei could also gain strength if, as forecast, a new younger generation of hard-line loyalists gains positions of power.
Going nuclear
The likely effect of a further increase in conservative self-confidence, our correspondent says, will be even less chance of compromise over Iran’s nuclear programme, and a yet more assertive foreign policy.
It is thought the reformists may struggle to hang on to the 40 or so seats they hold in the assembly.
They say the election is unfair but still urged Iran’s 44 million eligible voters to turn out for the country’s eighth parliamentary elections since its 1979 Islamic revolution.
President Ahmadinejad’s political opponents blame him for the three rounds of sanctions imposed on Iran by the United Nations over its nuclear programme.
The US, Israel and key Western powers accuse Iran of attempting to build a nuclear bomb, but Tehran insists it is only enriching uranium for a civilian energy programme.
