Footage broadcast by local media showed police entering the residence of Piero Corvetto, the former head of Peru's National Office of Electoral Processes (ONPE), in Lima's Miraflores district under a judicial warrant.
Peruvian police also carried out searches of up to 12 buildings as part of the probe, authorities said.
Peru's public prosecutor's office said the raid was carried out by the anti-corruption police unit alongside prosecutors, amid growing public allegations of irregularities in the electoral process.
Corvetto's lawyer Ricardo Sanchez Carranza told Reuters a judge authorised the search of his home but denied prosecutors' request for preliminary detention, adding that his client co-operated fully.
Prosecutor Raul Martinez, who is leading the case, ordered the seizure of mobile phones, laptops and documents from Corvetto's home, local broadcaster RPP reported.
Corvetto resigned on Tuesday, saying it was "necessary and unavoidable" for him to step down to help restore public confidence in the electoral process after logistical failures led to prolonged delays at polling stations and the release of election results.
He denied any wrongdoing in his resignation letter and said unresolved issues should be addressed through an impartial investigation.
Observers from the European Union have said they found no evidence of fraud.
The slow vote count has fuelled fraud allegations in Peru from several candidates.
Electoral authorities this week began reviewing thousands of contested ballots due to inconsistencies or errors on tally sheets, a process that has further delayed final results.
As of Friday morning, about 95 per cent of votes had been tallied, according to ONPE, with conservative candidate Keiko Fujimori leading with roughly 17 per cent of the vote, and a tight race for second place between progressive MP Roberto Sanchez and former Lima mayor Rafael Lopez Aliaga.
Sanchez's lead over Lopez Aliaga had widened to roughly 20,000 votes, from 14,000 earlier in the week.
Peru's National Jury of Elections has said final results will be announced by May 15, ahead of a scheduled presidential runoff between the top two candidates on June 7.
