Ahmadinejad entered the interior ministry's building that houses election headquarters to register as a candidate, Iranian media reported.
A number of prominent Iranian politicians also joined the campaign, including former parliament chairman Ali Larijani and Central Bank Governor Abdul Nasser Hemmati, among others, according to the reported.
Moreover, Iranian Minister of Culture and Islamic Guidance Mohammad Mehdi Esmaili has registered to run in the snap presidential election as well.
Under the approved electoral calendar, the registration of candidates will take place from May 30 to June 3, and eligibility checks will be conducted from June 4 to 10. The final list of candidates will be announced on June 11, Mehr reported.
Campaigning will be allowed for two weeks, from June 12 to June 26. A "day of silence" will be declared one day before the elections, during which campaigning is prohibited. The presidential election will take place on June 28. The second round, if necessary, will be held on July 5.