Owner and chairman Fawaz Al Hasawi confirmed the appointment via Twitter ahead of a 12.30pm press conference.
Former Forest favourite Pearce, whose last role was with England's Under-21 side, initially turned down the job following talks last week, citing family reasons.
Forest have been looking for a new boss since Al Hasawi dismissed Billy Davies on March 24 following a run of eight matches without a win, culminating in a 5-0 loss to bitter rivals Derby.
The Reds currently lie seventh in the Sky Bet Championship, two points adrift of a play-off place with seven games remaining.
The 51-year-old Pearce spent 12 years with Forest as a player and admitted on Wednesday that he still had a lot of affection for the club
''Forest have always been well supported whatever league they've been in, there's a rich history there,'' he said
''It's a great club and one that's very close to my heart.''
Gary Brazil is in temporary charge of first-team affairs at the two-time European champions and looks likely to remain at the helm until the end of the season
Source : PA
Source: PA