The PSG midfielder, who travelled to the UK from Paris by private jet, touched down late on Tuesday night before heading to Manchester to undergo medical tests.
The clubs agreed on a fee on Monday night after Manchester United’s Jason Wilcox headed to Paris to finalise negotiations. Wilcox was joined in the French capital by Matt Hargreaves, the club's director of player negotiations.
The deal for Ugarte is worth an initial £42million plus a further £8.4m in add-ons, taking the total fee to just north of £50m.
Negotiations with PSG accelerated after United were able to agree a £26m deal with Napoli over the sale of midfielder Scott McTominay. Meanwhile, United starlet Hannibal Mejbri has joined Burnley in a deal worth up to £9.5m.
PSG midfielder Manuel Ugarte has landed in the UK to complete his medical at Man United
McTominay travelled to Italy on Tuesday to finalise his exit from United, while Mejbri underwent part of his medical on Monday night.
Ugarte has not featured in either of PSG's first two games of the new Ligue 1 season, having made it clear that he wants to join United.
The midfielder is set to become Erik ten Hag's fifth signing of the summer transfer window.
The Dutchman has brought in striker Joshua Zirkzee, centre-halves Matthijs de Ligt and Leny Yoro, and full-back Noussair Mazraoui so far, focusing predominantly on bolstering United in defensive areas.
Ugarte, who is expected to protect the back four alongside Kobbie Mainoo in midfield, posted a cryptic message on social media ahead of jetting to England to tease fans about his imminent move to Old Trafford.
The Uruguayan kept his post short and sweet, tweeting nothing but the eyes emoji to indicate there was truth behind the rumours linking him to United.
Ugarte featured in 37 games for the French heavyweights last season as the club won Ligue 1 and the Coupe de France.
Before his move to the Parc de Princes, he had represented Sporting Lisbon 85 times over a two-year spell, having initially started his Portuguese club career playing for Famalicao.
Ugarte has also been capped 22 times at senior international level for Uruguay.
McTominay heads for the Old Trafford exit door after spending his entire club career to date in Manchester, having first become involved with the United youth system aged just five.
McTominay's last appearance for United came on Saturday in a 2-1 defeat at Brighton.