He will allegedly sign a long-term deal at Old Trafford after terms between the clubs were agreed.
Man United will pay £30m up-front for Lindelof, with almost £5m in bonuses if certain targets are met during his time in Manchester.
Portuguese daily O Jogo claim Benfica president Luis Filipe Vieira had travelled to England to negotiate the sales of Lindelof and his team-mate Nelson Semedo.
The 23-year-old has been massively linked with a move to Real Madrid, Barcelona and Newcastle, however, it seems like Old Trafford could be the preferred destination after a move in January fell through due to a payment owed to his former club Vasteras.
He signed a new four-and-a-half-year contract earlier this year, although the Portuguese boss will not be deterred as he has to bolster his defensive options before the start of next season.
The side will be looking for another defender just like Eric Bailly, who has taken the Premier League by storm and after scouting Lindelof throughout the season, it seems like Mourinho has been impressed with what he has to offer.