Vetters disqualified the presidential bids of 471 people, leaving four men to battle it out in the popular vote.
Supreme Leader Ayatollah Ali Khamenei offered his early endorsement to conservative incumbent Mahmud Ahmadinejad.
The three-week campaign season kicked off in earnest once the field was narrowed to four.
TV debates were a first in Iran presidential politics, with each candidate going one-on-one against each of his rivals.
Sparks flew during reformist Mir Hossein Musavi's debate with Ahmadinejad on June 3, the presumed front-runners.
Cleric and reformist candidate Mehdi Karrubi was among a handful of candidates defeated by Ahmadinejad in 2005.
An underdog, former Revolutionary Guards commander Mohsen Rezai brandished conservative credentials.
Musavi supporters donned green, while Ahmadinejad voters frequently brandished the national flag.
Ahmadinejad and Musavi backers confronted each other outside Tehran University after Friday prayers on June 6.
Musavi supporters hit Tehran's streets on June 8, when they formed an 18-kilometer human chain on Valiasr Avenue.
An Ahmadinejad supporter in Tehran on June 2
President Ahmadinejad and his wife at a campaign rally in Tehran on June 2
Musavi's wife, artist and former university chancellor Zahra Rahnavard, campaigned tirelessly for her husband.
Musavi rallies drew tens of thousands to sports stadiums in major cities.
Ahmadinejad supporters turned out at Sharif University on June 10.
With passions high and no opposition boycott in effect, there was a party-like atmosphere at the height of the campaign.