According to BBC Sport, Pereira was blindsided by the decision late on Tuesday, ending his stint that began in February when he replaced Sean Dyche.
Pereira successfully guided Forest to 16th in the Premier League and reached the Europa League semi-finals, marking the first time the club had reached a European semi-final since 1984. His coaching staff, including Filipe Almeida, Luis Miguel, Bruno Moura, Marco Knoop and Pedro Lopes, have also left the club. The decision means Forest will soon appoint their fifth manager in fewer than 12 months.