Former presidents Pedro Pablo Kuczynski, Alan Garcia and Alejandro Toledo all took money for their campaigns in exchange for pledges to have the Brazilian construction giant win local tenders, prosecutors said.
Prosecutor Jose Domingo Perez opened a preliminary investigation of money laundering against the trio, as well as three individuals close to each of them, according to a statement from his office.
The investigation stems from questioning of Jorge Barata, a Brazilian who was a former Odebrecht boss in Peru.
He told Brazilian investigators that he doled out millions of dollars to Peruvian presidential candidates between 2001 and 2016.
In the 2011 elections, Odebrecht gave money to four candidates, Barata told prosecutors: $1.2 million to Keiko Fujimori, son of former president Alberto Fujimori; $700,000 to Toledo; and $300,000 to Kuczynski.
Meanwhile, Barata said political aide Luis Alva Castro, who was close to Garcia 's campaign, received more than $200,000.
Fujimori is known to have been investigated over similar payoffs but was not named in this step.
Peruvian prosecutors have previously announced they are investigating former president Ollanta Humala (2011-2016) for allegedly taking $3 million in bribes from Odebrecht. Peru is the Latin American nation that has been most seriously rocked by the Odebrecht scandal, after Brazil itself.
President Martin Vizcarra -- who was ambassador to Canada as well as vice-president -- took office on March 23 after Kuczynski stepped down amid corruption allegations, shortly before he was to face impeachment.