Pereira held the position of sporting director at Italian Serie A side Fiorentina last season.
The Reds, who finished 16th in the Championship in 2015-16, are without a manager after parting company with caretaker boss Paul Williams in May.
"Forest has huge potential and I believe and hope I can contribute significantly in bringing the club back to the Premier League," said Pereira.
"It is a big honour and, at the same time, a great challenge to work with such a historical and important club as Nottingham Forest."
Pereira also worked as a CEO at Portuguese team Sporting Braga for 13 years, as they twice reached the Champions League group stage and the final of the Europa League in 2011.
"I want to sincerely thank the chairman for offering this opportunity to me," he continued.
"I respect deeply the history of the club but we have to look ahead and create the background for a new chapter of success, stability and victories.
"Our focus is to prepare the team for the coming season and to fulfil our ambitions. We need the support of all Nottingham Forest fans to achieve our goals."
Nottingham Forest have appointed Pedro Pereira as director of football.