Polling stations across Iran closed at midnight after sixteen hours. The Interior Ministry had extended the voting three times.
More than 56,400,000 Iranian people were eligible to vote.
Unofficial media reports suggest that more than 40 million people have voted in the election, which translates into a turnout of around 72 percent.
The ballot count has begun upon the formal closure of the polls.
There are four candidates seeking presidency in Iran, namely incumbent President Hassan Rouhani, Ebrahim Raisi, Mostafa Hashemitaba, and Mostafa Aqa-Mirsalim.
A run-off would be held a week later if none of the candidates wins a majority, which is at least 50 percent plus one vote.
Interior Minister Abdolreza Rahmani Fazli has quashed rumors about the outcome of the election, stressing that any official results would be made public only by his ministry.