The 54-year-old takes charge at the City Ground shortly after the dismissal of Postecoglou, who was relieved of his duties after only 39 days just minutes following Saturday’s 3-0 home defeat by Chelsea in the Premier League.
Dyche is Forest’s third full-time manager of the season already, with Nuno Espirito Santo having been sacked last month before replacing Graham Potter at West Ham.
He had been out of work since being sacked by Everton in January after less than two years in charge, previously spending a decade at Burnley and overseeing two Premier League promotions and a top-half finish as the division’s longest-serving manager before being dismissed in April 2022.
Dyche began his managerial career at Watford and already has a previous affinity with Forest as a player, having come through the youth system as a youngster when Brian Clough was in charge before leaving in 1990 without making a senior appearance.
Forest legends Ian Woan and Steve Stone are long-time members of Dyche’s backroom team and will join him at the City Ground.