Chelsea paid a Premier League record fee of 121 million euros to sign Enzo Fernandez as Joao Cancelo made a surprise move to Bayern Munich and Jorginho joined Arsenal on a frantic transfer deadline day in Europe.
Premier League clubs have once again massively outspent their rivals in a desperate scramble to strengthen their squads for the second half of the season.
World Cup winner Fernandez, whose transfer was announced by Portuguese club Benfica in the early hours of Wednesday, is Chelsea's eighth signing of the January window.
The £106.8 million fee eclipses the previous record of £100 million that Manchester City paid Aston Villa for Jack Grealish in 2021.
Fernandez, named Best Young Player of the World Cup for his displays during Argentina's successful campaign in Qatar, only joined Portuguese giants Benfica in July last year, for a reported fee of around £10 million.
The 22-year-old is understood to have signed an eight-and-half-year deal that will run until 2031.
Todd Boehly's consortium has spent hundreds of millions since buying Chelsea at the end of last season but the club are languishing in 10th place in the Premier League.
Bayern Munich signed Manchester City wing-back Cancelo on loan until the end of the season and have an option to buy him for a reported 70 million euros.
The 28-year-old Portuguese defender joined City from Juventus in 2019 but has been a peripheral figure in Pep Guardiola's team since the World Cup.
"FC Bayern is a great club, one of the best in the world, and it's enormous motivation for me to now play alongside these extraordinary players," Cancelo said.
Premier League leaders Arsenal snapped up Italy midfielder Jorginho from Chelsea for a reported fee of £12 million.
Jorginho, who is understood to have signed an 18-month deal at the Emirates Stadium, told Arsenal.com: "I'm very excited for this new challenge and I just can't wait to be on the pitch.
"Everything has happened so fast. I was a bit surprised, but I took the opportunity of this amazing challenge."
The Gunners, bidding to win their first Premier League crown since 2004, signed Belgium forward Leandro Trossard from Brighton and Poland defender Jakub Kiwior from Italian side Spezia earlier this month.
Arsenal's north London rivals Tottenham announced the signing of defender Pedro Porro from Sporting Lisbon minutes before the deadline.
The right-back has signed on loan until the end of the season with an obligation to make the move permanent at the end of the season.
Manchester United announced they had signed Bayern Munich midfielder Marcel Sabitzer on loan early Wednesday.
United were forced into deadline-day action on Tuesday following an ankle injury to Christian Eriksen, which is set to rule the Denmark midfielder out until early May.
Manager Erik ten Hag completed the loan signing of Netherlands forward Wout Weghorst earlier in the month.
High-flying Newcastle have followed up their signing of Anthony Gordon from Everton by securing Scotland Under-21 full-back Harrison Ashby from West Ham.
Relegation-threatened Bournemouth brought in Ukraine defender Illia Zabarnyi from Dynamo Kyiv for a reported fee of around £24 million before Sassuolo and Ivory Coast midfielder Hamed Traore became their sixth signing of the month.
Nottingham Forest continued the dramatic overhaul of their squad since they won promotion last year, signing Atletico Madrid defender Felipe and Newcastle midfielder Jonjo Shelvey.
Forest also brought in Paris Saint-Germain goalkeeper Keylor Navas on loan until the end of the season.
Leicester signed Australia defender Harry Souttar from Stoke on a five-and-a-half year deal, with Ayoze Perez joining Real Betis for the rest of the season.
Southampton spent a potential club record on Kamaldeen Sulemana from Rennes, with the Ghana forward's arrival costing a potential £22 million.
Belgium international Thorgan Hazard has signed for Dutch club PSV Eindhoven on loan from Borussia Dortmund.