"Sergio Conceicao has informed FC Nantes of his irreversible will of leaving Nantes to join Porto, without delay," Nantes said in a statement.
"An agreement has been reached between Sergio Conceicao, his three assistants, and Porto."
The former Portugal midfielder joined Nantes last December when they were second from bottom in Ligue 1. He guided the club away from the relegation zone and up to seventh place at the end of the season.
Conceicao agreed to a contract extension until 2020 before being offered the Porto job.
"I did everything to give him the means to continue his mission," said Nantes president Waldemar Kita.
"Good luck to him."
(Reporting by Julien Pretot; Editing by Toby Davis)
