The 30-year-old has played for Real since 2013, earning five Champions Leagues and three La Liga championships.
Casemiro will sign a four-year contract with an additional year’s option for an initial sum of £60 million plus £10 million in add-ons.
United, now last in the Premier League, will play Liverpool on Monday at Old Trafford.
After fulling his transfer, Casemiro will become one of Manchester United’s highest-paid players. He follows defender Lisandro Martinez, fullback Tyrell Malacia from Feyenoord, and midfielder Christian Eriksen as the club’s fourth acquisition.
To strengthen Erik ten Hag’s midfield, United have shifted their focus to Casemiro after negotiations to buy Adrien Rabiot from Juventus fell through due to the player’s demands.
The chase of Barcelona player Frenkie de Jong by Manchester United is almost over after this agreement.
The club admits it is very improbable they will get De Jong and Casemiro in the same transfer window, although not entirely ruling out the possibility of doing so at some time in the future.
Casemiro won’t be able to play in Monday’s match against Liverpool since the move would be too late.
Comparing Casemiro’s stats to those of other center midfielders in La Liga last season, one can see his influence.
The Brazilian international finished first for successful blocks, second for tackles made behind Sergio Busquets of Barcelona, and third overall for possession gained. In the latter category, Mikel Merino of Real Sociedad won first place, with Busquets coming in second.
He also assisted Real’s offense, being seventh in the league among center midfielders for forwarding passes and joint-sixth for shoots.
In 2014–15, Casemiro spent a season on loan at Porto in Portugal before returning to Spain as Real Madrid exercised his buy-back clause.
He has 222 appearances and 24 goals for the Spanish powerhouses.