Cavani, who has signed a one-year contract with the option to extend for a further year, moves to Old Trafford on a free transfer following his release from Paris St Germain this summer.
Cavani on the club website: “Manchester United is one of the greatest clubs in the world, so it is a real honour to be here. I’ve worked really hard during the time off and I feel eager to compete and represent this incredible club.”
United are understood to have agreed a fee for £13.5million plus £1.8million in potential add-ons with the Portuguese club for left-back Telles.
Telles told his new club’s website: “To join a club with the prestige of Manchester United is a huge honour.
“You have to work hard to get to this moment in your career and now I am coming to this club, I can promise that I will give everything in my heart to be a success here.”
United have also reached an agreement to sign 18-year-old Atalanta winger Amad Diallo, who will join the Premier League club in January subject to a medical, personal terms and a work permit.
In addition, United have announced the signing from Sochaux of centre-back Willy Kambwala, who will join the Under-18s squad, while Chris Smalling has completed a permanent move to Roma.
Elsewhere, Southampton have been in contact with Everton about re-signing Theo Walcott after the Merseyside club landed Ben Godfrey from Norwich.
With new signing James Rodriguez having made the wide-right spot his own thanks to an excellent start to his Goodison Park career, Walcott’s first-team chances look like being limited.
The 31-year-old is in the final year of his contract and while a return to Saints is thought to be his preferred choice, he has also been linked with Crystal Palace, West Ham, Fulham and Newcastle.
Norwich announced they had received a club-record fee for Godfrey, whose deal ties him to Everton until the end of June 2025.
The 22-year-old made 30 appearances for relegated Norwich in the Premier League last season, and had been linked to a number of top-flight clubs this transfer window.
The centre-back completed a medical with the Premier League leaders over the weekend before the deal was announced on Monday morning.
Arsenal midfielder Matteo Guendouzi joined Bundesliga outfit Hertha Berlin on a season-long loan deal.
The France Under-21 international made 82 appearances since joining the Gunners from Lorient two years ago but he found himself surplus to requirements under Mikel Arteta this season.
Fulham are pushing to sign Chelsea midfielder Ruben Loftus-Cheek on loan, the PA news agency understands.
Manager Scott Parker still wants to bolster his defence ahead of the transfer deadline, but is also keen to add England star Loftus-Cheek to the Craven Cottage ranks.
The 24-year-old only featured once for Chelsea this term, in the 3-1 Premier League win at Brighton on the opening weekend, and has spent the last 16 months battling a torn Achilles tendon injury.
Tottenham held talks with a view to signing Swansea center-back Joe Rodon, while Ryan Sessegnon joined Bundesliga outfit Hoffenheim on loan for the rest of the season.
The 20-year-old struggled to make an impact since joining Spurs for £25million last summer and was sent out to get some game-time.
Wolves defender Ruben Vinagre completed a season-long loan move to Olympiacos, with an option for the Greek champions to make the deal permanent, while Chelsea midfielder Tiemoue Bakayoko joined Napoli on loan for the rest of the campaign.
Saints allowed Sofiane Boufal and Guido Carrillo to leave on free transfers to Angers and Elche respectively, while defender Wesley Hoedt rejoined his previous club Lazio on loan.
Leicester forward Rachid Ghezzal joined Besiktas on a season-long loan. The Algeria international spent last term on a temporary deal with Fiorentina.