The Portuguese coach, 57, has penned a deal to the end of the season.
He takes over at the City Ground from Sean Dyche, who was sacked early on Thursday morning.
Multiple local media sources say Forest are expected to confirm Pereira's appointment sometime on Saturday. Pereira returns to the Premier League after his dismissal by Wolves earlier this season.
He follows Nuno Espirito Santo, Ange Postecoglou and Dyche as Forest manager since September.
Forest currently sit 17th on the Premier League table, three points ahead of 18th place West Ham.