Other new high-profile signings include former Paris-Saint Germain striker Zlatan Ibrahimovic and Ivorian defender Eric Bailly
Jose Mourinho officially started work as Manchester United manager at the club's Carrington training base on Monday.
The Portuguese man travelled to Manchester by train on Sunday night and posted a video on Instagram showing his arrival at Picadilly station, saying: "I am here/UNITED we can".
He arrived at Carrington with goalkeeping coach Silvino Louro on Monday morning.
The 53-year-old was appointed as United boss in May after the sacking of Dutchman Louis van Gaal.
Van Gaal won the FA Cup in his final match in charge, but in the Premier League he led the Red Devils to only fourth and fifth-placed finishes in his two seasons.
Mourinho has already begun shaping his new squad to grace Old Trafford next season, with former Paris-Saint Germain striker Zlatan Ibrahimovic and Ivorian defender Eric Bailly high-profile new signings.
The former Chelsea coach is also close to concluding a deal for Borussia Dortmund's Armenian playmaker Henrikh Mkhitaryan.
The German club announced on Saturday that Mkhitaryan was close to finalising a deal with United after they had accepted an "enormously valuable offer".
Mourinho, who has won the Champions League with Porto and Inter Milan, saw his second spell at Stamford Bridge unceremoniously ended after a disastrous start to the Blues' league title defence last term.
Mourinho is set to be formally unveiled as United head coach on Tuesday before the players start pre-season training the following day.
The three-time European champions take on Dortmund and rivals Manchester City on their pre-season tour of China later in July.