Ahmadinejad and his former deputy Hamid Baqaee signed up at Iran’s Interior Ministry in Tehran on Wednesday to run for president.
Ahmadinejad was a two-term president taking the office for 8 years, before President Hassan Rouhani won the 2013 election.
After conclusion of the process of registration of the applicants, the Guardian Council will have five days for vetting process to assess the qualification of the individuals.
The final list of the candidates will be released afterwards, and they will have 20 days for electoral campaigns, before the election day on May 19.
The number of eligible voters in the upcoming election is estimated to be around 1.5 million higher than the 50.5 million in the previous round four years ago.