The 57-year-old takes over at the City Ground from Sean Dyche, who was sacked early on Thursday morning.
Vitor Pereira has a deãl until the end of next season to become Nottingham Forest’s fourth manager of the campaign and help them avoid relegation from the Premier League.
Forest are yet to officially announce the Portuguese’s appointment, but he is set to return for another spell in English football, having been axed by Wolves in November after 11 months in charge.
The Tricky Trees are 17th in the Premier League, three points above the drop zone, after two wins in their last 10 games.
Pereira follows Nuno Espirito Santo, Ange Postecoglou and Dyche as Forest manager since September.
They sacked Dyche after being held to a disappointing goalless draw by bottom club Wolves on Wednesday.
Pereira, who won 14 of his 38 games in charge of Wolves and helped them stay up last season, quickly emerged as the preferred replacement, having worked previously under Forest owner Evangelos Marinakis at Greek club Olympiacos.
He won the title and Greek Cup in 2014-15 in his six months in charge, before leaving for Fenerbahce.
Pereira joined Wolves in December 2024, but was sacked three months ago with the club on two points from their first 10 league matches.
He started his managerial career with Portuguese club Sanjoanense in 2004 and, following spells in Germany, China, Brazil and Saudi Arabia, he is set to embark on his 15th role.
Forest sacked Nuno just three games into the season in September after he declared his relationship with Marinakis had deteriorated, despite finishing seventh and qualifying for Europe last season.
Australian Postecoglou was appointed as his successor but lasted only 39 days after failing to win any of his eight league games in charge – drawing two and losing six.
Dyche’s arrival appeared to bring stability, winning seven of his opening 12 games, but the poor recent run saw Forest fail to pull away from danger, with players unconvinced by his methods.
Several were summoned to see owner Marinakis after the Wolves draw, with opinions also canvassed following Friday’s 3-1 defeat at fellow strugglers Leeds.
Pereira’s first game in charge will be the first leg of the Europa League knockout round play-off tie against his former club Fenerbahce in Turkey on Thursday, before Forest host Liverpool in the Premier League on Sunday, 22 February.