The agreement comes after United had two previous offers rejected by Brentford. The second offer was for more than £60 million. The deal is a significant signing for United, who have been looking to strengthen their attack.
Mbeumo, 25, is expected to be announced as a United player after the club's first pre-season friendly against Leeds United in Stockholm on Saturday. He may be announced on Sunday, either in the afternoon or on the day after the game.
The signing of Mbeumo is part of United's ongoing efforts to strengthen their squad. The club has already completed deals for Wolves striker Matheus Cunha and teenage full-back Diego Leon.
However, United still needs to sell some of their unwanted players, including Marcus Rashford, Alejandro Garnacho, Antony, Jadon Sancho, and Tyrell Malacia. The club is trying to sell these players before the season begins to avoid going against financial rules.
The signings of Cunha, Mbeumo, and Leon are a positive step for United, but the club still needs to balance its spending with the need to sell some of its unwanted players.