Philippe Coutinho said of his move to Barcelona: "I am very happy, it's a dream come true and I hope to be up to the job on the field."
The January transfer window closes in England at 23:00 GMT and at 00:00 in Scotland on Wednesday, 31 January.
Keep up to date with all of the confirmed deals in our list below.
Signings confirmed between September and December can be found on our previous transfer page.
For all the latest rumours check out the gossip page and, for all the manager ins and outs, see our list of current bosses.
Transfer deadline day live - latest news on rumours and completed dealsSelected deals still to happenDortmund agree loan deal for Chelsea striker BatshuayiMahrez hands in transfer request as Man City make bidWest Ham want to sign Everton's Schneiderlin on loanCompleted deals31 January
Premier League
11:13 Pierre-Emerick Aubameyang [Borussia Dortmund - Arsenal] £56m
English Football League
12:00 Ben Hall [Brighton - Notts County] Loan
11:59 Tom Anderson [Burnley - Doncaster] Loan
10:30 Matt Penney [Sheffield Wednesday - Mansfield] Loan
30 January
Premier League
Jack Harrison [New York City - Manchester City] Undisclosed
Aymeric Laporte [Athletic Bilbao - Manchester City] £57m
Dodi Lukebakio [Anderlecht - Watford] Undisclosed
Emerson Palmieri [Roma - Chelsea] £17.6m
Sandro Ramirez [Everton - Sevilla] Loan
English Football League
Karlan Ahearne-Grant [Charlton - Crawley] Loan
Andy Boyle [Preston - Doncaster] Loan
Tobias Figueiredo [Sporting Lisbon - Nottingham Forest] Loan
Jack Harrison [Manchester City - Middlesbrough] Loan
Diogo Jota [Atletico Madrid - Wolves] Undisclosed*
Jota currently on season-long loan, deal to become permanent in the summer
Joe Rodon [Swansea - Cheltenham] Loan
Chiedozie Ogbene [Limerick - Brentford] Undisclosed
Charlie Raglan [Oxford - Port Vale] Loan
Alex Revell [Northampton - Stevenage] Free
Josh Tymon [Stoke - MK Dons] Loan
Kevin van Veen [Scunthorpe - Northampton] Undisclosed
Elliott Ward [Blackburn - MK Dons] Loan
Gregg Wylde [Plymouth - Morecambe] Loan
International
Marcus McGuane [Arsenal - Barcelona] Undisclosed
Roque Mesa [Swansea - Sevilla] Loan
Ahmed Musa [Leicester - CSKA Moscow] Loan
Krystian Nowak [Hearts - Panionios] Free
Danny Wilson [Rangers - Colorado Rapids] Undisclosed
29 January
Premier League
Gerard Deulofeu [Barcelona - Watford] Loan
Ali Gabr [Zamalek - West Brom] Loan
Daniel Sturridge [Liverpool - West Brom] Loan
Leonardo Ulloa [Leicester - Brighton] Loan
English Football League
Luke Amos [Tottenham - Stevenage] Loan
Tim Cahill [Unattached - Millwall]
Tommy Elphick [Aston Villa - Reading] Loan
Adam King [Swansea - Mansfield] Loan
Caolan Lavery [Sheffield United - Rotherham] Loan
Connor Mahoney [Bournemouth - Barnsley] Loan
Boris Mathis [Everton - Northampton] Loan
Justin Shaibu [Brentford - Walsall] Loan
Ashley Smith-Brown [Manchester City - Oxford] Loan
George Taft [Mansfield - Cambridge] Loan
Harry Toffolo [Norwich - Millwall] Undisclosed
Anton Walkes [Tottenham - Portsmouth] Loan
Scottish Premiership
Charly Musonda [Chelsea - Celtic] Loan
Aaron Tshibola [Aston Villa - Kilmarnock] Loan
International
Isma Goncalves [Hearts - Pakhtakor Tashkent] Undisclosed
Adrian Popa [Reading - Al-Taawoun] Loan
Diafra Sakho [West Ham - Rennes] Undisclosed
28 January
International
Loic Remy [Las Palmas - Getafe] Loan
27 January
English Football League
Shaun Donnellan [West Brom - Yeovil] Free
Stuart Moore [Barrow - Swindon] Free
International
Pietro Pellegri [Genoa - Monaco] Undisclosed
26 January
English Football League
Cameron Belford [Stranraer - Forest Green] Free
Darren Bent [Derby - Burton] Loan
Alex Fisher [Motherwell - Yeovil] Free
Sullay Kaikai [Crystal Palace - Charlton] Loan
Matty Lund [Burton - Bradford] Loan
Ryan McGowan [Al-Sharjah - Bradford] Free
Navid Nasseri [Unattached - Gillingham]
Duckens Nazon [Wolves - Oldham] Loan
Ryan Seager [Southampton - Yeovil] Loan
Ben Sheaf [Arsenal - Stevenage] Loan
Cole Stockton [Hearts - Carlisle] Free
Kris Twardek [Millwall - Carlisle] Loan
Stephen Warnock [Burton - Bradford] Loan
Mallik Wilks [Leeds - Grimsby] Loan
Scottish Premiership
Michael Devlin [Hamilton - Aberdeen] Undisclosed
25 January
Premier League
Guido Carrillo [Monaco - Southampton] Undisclosed
Joao Mario [Inter Milan - West Ham] Loan
Tony Gallagher [Falkirk - Liverpool] £200,000
Curtis Thompson [Notts County - Wycombe] Loan
English Football League
Kai Bruenker [SC Freiburg - Bradford] Undisclosed
Lois Diony [Saint-Etienne - Bristol City] Loan
Jay Fulton [Swansea - Wigan] Loan
Onel Hernandez [Eintracht Braunschweig - Norwich] Undisclosed
Moritz Leitner [FC Augsburg - Norwich] Loan
Kazenga LuaLua [Brighton - Sunderland] Free
Shaun Miller [Carlisle - Crewe] Loan
Kevin O'Connor [Preston - Fleetwood] Loan
Matty Palmer [Burton - Rotherham] Undisclosed
Jason Shackell [Derby - Millwall] Loan
Dennis Srbeny [Paderborn - Norwich] Undisclosed
Axel Tuanzebe [Manchester United - Aston Villa] Loan
Scottish Premiership
Danny Amankwaa [FC Copenhagen - Hearts] Undisclosed
Greg Docherty [Hamilton - Rangers] Undisclosed
24 January
English Football League
Paul Rooney [Millwall - Colchester] Undisclosed
Scottish Premiership
Marios Ogboe [OFI Crete - Hamilton] Free
Peter Hartley [Blackpool - Motherwell] Undisclosed
Harry Souttar [Stoke - Ross County] Loan
23 January
Premier League
Aaron Lennon [Everton - Burnley] Undisclosed
Jaroslaw Jach [Zagłebie Lubin - Crystal Palace] Undisclosed
Kenedy [Chelsea - Newcastle] Loan
English Football League
Franck Moussa [unattached - Gillingham]
Scottish Premiership
David Ngog [unattached - Ross County]
International
Ritchie de Laet [Aston Villa - Royal Antwerp] Loan
Lassana Diarra [unattached - Paris St-Germain] Free
22 January
Premier League
Henrikh Mkhitaryan [Man Utd - Arsenal] Swap for Alexis Sanchez
Erdal Rakip [Benfica - Crystal Palace] Loan
Alexis Sanchez [Arsenal - Man Utd] Swap for Henrikh Mkhitaryan
English Football League
Ryan Loft [Tottenham - Exeter] Loan
Kenny McLean [Aberdeen - Norwich] Undisclosed*
*McLean loaned back to Aberdeen for rest of 2017-18 season
Matt Targett [Southampton - Fulham] Loan
Michal Zyro [Wolves - Charlton] Loan
International
Mateusz Klich [Leeds - FC Utrecht] Loan
Tommy Smith [Ipswich - Colorado Rapids] Undisclosed
19 January
Premier League
Jurgen Locadia [PSV Eindhoven - Brighton] £14m
English Football League
Gboly Ariyibi [Nottingham Forest - Northampton] Loan
Dan Barlaser [Newcastle - Crewe] Loan
Amari'i Bell [Fleetwood - Blackburn] Undisclosed
Tahvon Campbell [West Brom - Forest Green] Loan
Cameron Carter-Vickers [Tottenham - Ipswich] Loan
Ilias Chatzitheodoridis [Brentford - Cheltenham] Loan
Simon Church [Scunthorpe - Plymouth] Free
Kyle Edwards [West Brom - Exeter] Loan
Stephen Gleeson [Birmingham - Ipswich] Free
Zak Jules [Shrewsbury - Port Vale] Loan
Jonny Maxted [Guiseley - Accrington] Undisclosed
Harry McKirdy [Aston Villa - Crewe] Loan
George Miller [Middlebrough - Bury] Loan
Dani Pinillos [Cordoba - Barnsley] Undisclosed
Randell Williams [Watford - Wycombe] Loan
International
Leon Goretzka [Schalke - Bayern Munich] Free*
Robin van Persie [Fenerbahce - Feyenoord] Free
*Deal to be completed in the summer transfer window
18 January
Premier League
Kostas Stafylidis [Augsburg - Stoke] Loan
English Football League
Dan Agyei [Burnley - Blackpool] Loan
George Cooper [Crewe - Peterborough] Undisclosed
Mihai Dobre [Bournemouth - Rochdale] Loan
Adam Forshaw [Middlesbrough - Leeds] £4.5m
Luke Hannant [Gateshead - Port Vale] Undisclosed
Joey Pelupessy [Heracles Almelo - Sheffield Wednesday] Undisclosed
Callum Reilly [Bury - Gillingham] Loan
Zak Vyner [Bristol City - Plymouth] Loan
Alex Whitmore [Burnley - Chesterfield] Free
Scottish Premiership
Steven Naismith [Norwich - Hearts] Loan
International
Nicolai Brock-Madsen [Birmingham - Cracovia] Loan
Ragnar Sigurdsson [Fulham - FC Rostov] Undisclosed
17 January
Premier League
Theo Walcott [Arsenal - Everton] £20m+
English Football League
Brandon Comley [QPR - Colchester] Undisclosed
Marko Grujic [Liverpool - Cardiff] Loan
Sam Hart [Blackburn - Rochdale] Loan
Martin Samuelsen [West Ham - Burton] Loan
Marcus Tavernier [Middlesbrough - MK Dons] Loan
International
Liam Henderson [Celtic - Bari] Undisclosed
Deniss Rakels [Reading - Cracovia] Loan
16 January
English Football League
Keshi Anderson [Crystal Palace - Swindon] Undisclosed
Shane Blaney [Finn Harps - Doncaster] Undisclosed
Kean Bryan [Manchester City - Oldham] Loan
Joe Bunney [Rochdale - Northampton] Undisclosed
Cameron Jerome [Norwich - Derby] Undisclosed
Jack Payne [Huddersfield - Blackburn] Loan
Scottish Premiership
Tom Aldred [Bury - Motherwell] Loan
Russell Martin [Norwich - Rangers] Loan
International
Michael Madl [Fulham - Austria Vienna] Undisclosed
Erik Sviatchenko [Celtic - FC Midtjylland] Loan
15 January
English Football League
Jack Byrne [Wigan - Oldham] Undisclosed
Marcus Edwards [Tottenham - Norwich] Loan
Ricky Holmes [Charlton - Sheffield United] Undisclosed
Joe Pigott [Maidstone - AFC Wimbledon] Undisclosed
Marc Richards [Northampton - Swindon] Free
Scottish Premiership
Jason Cummings [Nottingham Forest - Rangers] Loan
13 January
Premier League
Fousseni Diabate [Gazelec Ajaccio - Leicester] Undisclosed
International
Arda Turan [Barcelona - Istanbul Basaksehir] Loan
12 January
Premier League
Alex Pritchard [Norwich - Huddersfield] Undisclosed
English Football League
Ollie Banks [Oldham - Swindon] Loan
Isaac Buckley-Ricketts [Manchester City - Oxford] Loan
Harry Charsley [Everton - Bolton] Loan
Callum Guy [Derby - Bradford] Loan
Noor Husin [Crystal Palace - Notts County] Undisclosed
Ryan Kent [Liverpool - Bristol City] Loan
Nathan McGinley [Middlesbrough - Wycombe]
Tafari Moore [Arsenal - Wycombe] Loan
Charlie Rowan [Watford - Accrington] Loan
James Vaughan [Sunderland - Wigan] Undisclosed
Billy Waters [Northampton - Cambridge] Loan
Yanic Wildschut [Norwich - Cardiff] Loan
Danny Williams [Dundee - Accrington] Free
Jordan Williams [Rochdale - Lincoln] Loan
11 January
International
Francis Coquelin [Arsenal - Valencia] £12m
English Football League
Cameron Brannagan [Liverpool - Oxford] Undisclosed
Laurens de Bock [Club Brugge - Leeds] Undisclosed
Akeel Francis [Rotherham - Accrington] Free
Lee Frecklington [Rotherham - Lincoln] Undisclosed
Paul Green [Oldham - Crewe] Loan
Billy Knott [Lincoln - Rochdale] Loan
Bernard Mensah [Aldershot - Bristol Rovers] Undisclosed
Connor Simpson [Hartlepool - Preston] Undisclosed
Michael Smith [Bury - Rotherham] Undisclosed
Ivan Toney [Newcastle - Scunthorpe] Loan
Jordan Turnbull [Coventry - Northampton] Free
Matty Virtue [Liverpool - Notts County] Loan
Ben Whiteman [Sheffield United - Doncaster] Undisclosed
Donovan Wilson [Wolves - Port Vale] Loan
Kane Wilson [West Brom - Exeter] Loan
Ryan Yates [Nottingham Forest - Scunthorpe] Loan
Offrande Zanzala [Derby - Accrington] Loan
Scottish Premiership
Demetri Mitchell [Manchester United - Hearts] Loan
10 January
English Football League
Lee Evans [Wolves - Sheffield United] £750,000
Joe Ward [Woking - Peterborough] Undisclosed
James Wilson [Manchester United - Sheffield United] Loan
Scottish Premiership
Chrysovalantis Kozoronis [Unattached - Hamilton]
Chidi Nwakali [Manchester City - Aberdeen] Loan
9 January
Premier League
Moritz Bauer [Rubin Kazan - Stoke] Undisclosed
Georges-Kevin Nkoudou [Tottenham - Burnley] Loan
English Football League
Elijah Adebayo [Fulham - Cheltenham] Loan
Adam Armstrong [Newcastle - Blackburn] Loan
Ryan Delaney [Burton - Rochdale] Undisclosed
Luke Hendrie [Burnley - Shrewsbury] Undisclosed
Haydn Hollis [Notts County - Forest Green] Free
Yosuke Ideguchi [Gamba Osaka - Leeds] Undisclosed
Ryan Leonard [Southend - Sheffield United] Undisclosed
Ben Pringle [Preston - Oldham] Loan
Scottish Premiership
Nadir Ciftci [Celtic - Motherwell] Loan
Jeremy Malherbe [Unattached - Dundee]
Greg Tansey [Aberdeen - Ross County] Loan
International
Yosuke Ideguchi [Leeds - Cultural Leonesa] Loan
Carlos Pena [Rangers - Cruz Azul] Loan
8 January
English Football League
Jake Clarke-Salter [Chelsea - Sunderland] Loan
Zeus de la Paz [Cincinnati Dutch Lions - Oldham] Free
Paul Downing [MK Dons - Blackburn] Undisclosed
Jack Livesey [Partick Thistle - Burton] Undisclosed
Joe Lumley [QPR - Blackpool] Loan
Kieffer Moore [Ipswich - Barnsley] Undisclosed
Richard O'Donnell [Rotherham - Northampton] Undisclosed
Charles Vernam [Derby - Grimsby] Loan
Jamie Walker [Hearts - Wigan] Undisclosed
Scottish Premiership
Jamie Maclaren [SV Darmstadt 98 - Hibernian] Loan
International
Philippe Coutinho [Liverpool - Barcelona] £142m
Emilio Nsue [Birmingham - Apoel] Undisclosed
Jack Price [Wolves - Colorado Rapids] Undisclosed
7 January
English Football League
Toumani Diagouraga [Plymouth - Fleetwood] Free
International
Kevin Mirallas [Everton - Olympiakos] Loan
6 January
English Football League
Kundai Benyu [Celtic - Oldham] Loan
5 January
Premier League
Ross Barkley [Everton - Chelsea] £15m
Cenk Tosun [Besiktas - Everton] £27m
English Football League
Marcus Barnes [Southampton - Yeovil] Loan
Jack Bridge [Southend - Northampton] Undisclosed
Jonny Edwards [Hull - Woking] Loan
Shay Facey [Manchester City - Northampton] Undisclosed
Callum Johnson [Middlesbrough - Accrington] Undisclosed
Gethin Jones [Everton - Fleetwood] Undisclosed
Jake Kean [Sheffield Wednesday - Grimsby] Loan
Max Lowe [Derby - Shrewsbury] Loan
Sanmi Odelusi [Colchester - Cheltenham] Free
Aaron Ramsdale [Bournemouth - Chesterfield] Loan
Reuben Reid [Exeter - Forest Green] Undisclosed
Liam Walsh (Everton - Bristol City] Undisclosed
Corey Whelan [Liverpool - Yeovil] Loan
Lewis Wing [Middlesbrough - Yeovil] Loan
Scottish Premiership
Lewis Morgan [St Mirren - Celtic] Undisclosed
Lewis Morgan [Celtic - St Mirren] Loan
4 January
Premier League
Konstantinos Mavropanos [PAS Giannina - Arsenal] Undisclosed
English Football League
Jared Bird [Barnsley - Yeovil] Loan
Rob Dickie [Reading - Oxford] Undisclosed
Aaron Drinan [Waterford - Ipswich] Undisclosed
Jimmy Dunne [Burnley - Accrington] Loan
Gavin Gunning [Port Vale - Forest Green] Free
Zavon Hines [Unattached - Chesterfield]
Paul Jones [Norwich - Exeter] Loan
Josh Kay [Barnsley - Chesterfield] Loan
Tom King [Millwall - Stevenage] Loan
Cameron McGeehan [Barnsley - Scunthorpe] Loan
Sid Nelson [Millwall - Chesterfield] Loan
Farrend Rawson [Derby - Forest Green] Undisclosed
Connor Ripley [Middlesbrough - Bury] Loan
Ike Ugbo [Chelsea - MK Dons] Loan
Scottish Premiership
Scott Bain [Dundee - Hibernian] Loan
International
Prince Oniangue [Wolves - Angers] Loan
3 January
English Football League
Billy Bodin [Bristol Rovers - Preston] Undisclosed
Peter Clarke [Oldham - Bury] Loan
Sylvain Deslandes [Wolves - Portsmouth] Loan
George Dobson [Sparta Rotterdam - Walsall] Undisclosed
Ryan Gondoh [Maldon & Tiptree - Colchester] Undisclosed
Aapo Halme [HJK Helsinki - Leeds] Undisclosed
James Hanson [Sheffield United - Bury] Loan
Jordan Maguire-Drew [Brighton - Coventry] Loan
Stephy Mavididi [Arsenal - Charlton] Loan
Rafael Mir [Valencia - Wolves] Undisclosed
Junior Ogedi-Uzokwe [Maldon & Tiptree - Colchester] Undisclosed
Hildeberto Pereira [Legia Warsaw - Northampton] Loan
Adam Phillips [Norwich - Cambridge] Loan
Connor Ronan [Wolves - Portsmouth] Loan
Scottish Premiership
Sean Goss [QPR - Rangers] Loan
Curtis Main [Portsmouth - Motherwell] Undisclosed
International
Yeni Ngbakoto [QPR - Guingamp] Undisclosed
Daniel O'Shaughnessy [Cheltenham - HJK Helsinki] Free
2 January
Premier League
Terence Kongolo [Monaco - Huddersfield] Loan
English Football League
Paddy Madden [Scunthorpe - Fleetwood] Undisclosed
Danny Rowe [Ipswich - Lincoln] Loan
1 January
English Football League
Dior Angus [Redditch - Port Vale] Undisclosed
Manny Onariase [Rotherham - Cheltenham] Loan
Scottish Premiership
Scott Bain [Dundee - Hibernian] Loan
Pre-arranged deals that went through this month
Premier League
Viktor Gyokeres [IF Brommapojkarna - Brighton] Undisclosed
Adrien Silva [Sporting Lisbon - Leicester] £22m
Virgil van Dijk [Southampton - Liverpool] £75m
Scottish Premiership
Marvin Compper [RB Leipzig - Celtic] £1m
Declan John [Cardiff - Rangers] Undisclosed
English Football League
Josh Barrett [Reading - Coventry] Loan
Dayle Grubb [Weston-super-Mare - Forest Green] Undisclosed
Yosuke Ideguchi [Gamba Osaka - Leeds] £500,000 (reported)
Emiliano Marcondes [Nordsjaelland - Brentford] Undisclosed
Patrick McEleney [Dundalk - Oldham] Undisclosed
Louis Moult [Motherwell - Preston] £500,000 (reported)
Liam Noble [Forest Green - Notts County] Free
Alex Whittle [York - Forest Green] Free
International
Diego Costa [Chelsea - Atletico Madrid] Undisclosed
The page covers signings by Premier League, Championship and Scottish Premiership clubs, along with selected deals from overseas and the Scottish Championship.
Source: bbc.com