Former president Akbar Rafsanjani and a top aide to incumbent Mahmoud Ahmadinejad were among the hopefuls to register as candidates just ahead of Saturday's deadline.
The next step will be a final vetting of the field by the Guardian Council, which is controlled by Supreme Leader Ayatollah Khamenei. Genevive Abdo, an analyst at the Stimson Center's Middle East Program in Washington, told CNN it was unlikely the council would give a green light to allies of Ahmadinejad, who had a history of friction with Iran's influential conservative clerics during his two terms.
Ahmadinejad is barred by the Iranian constitution from seeking a third consecutive term. His right-hand man, Esfandiar Rahim Mashaei, filed for the election Saturday.
Blocking Mashaei's candidacy could bolster the moderate Rafsanjani, who has been a critic of Ahmadinejad and served two non-consecutive terms as president.
Other notable names added to the field Saturday were Saeed Jalili, Iran's lead nuclear negotiator, and former foreign minister Ali-Akbar Velayati, who is currently a senior adviser to Khamenei and has promised to protect the country's nuclear program while also seeking to ease Western sanctions, China's Xinhua news agency said.