Manchester City confirmed Balotelli had completed his move to AC Milan quite early into the day. Milan said Balotelli has signed a four-and-a-half year contract - the fee is understood to be £19 million, rising to £22 million.
However, it was Beckham who stole the show after he signed for Paris St Germain and promised to donate his entire salary to charity.
The former England captain signed a five-month deal with the Ligue 1 leaders after turning down offers from England, and his generous offer could see a Paris children's charity receive up to £3 million.
"We decided on something quite unique. In this time I won't receive any salary. My salary will go to a local children's charity in Paris," said Beckham, who joined PSG as a free agent after leaving Major League Soccer side the Los Angeles Galaxy in December.
"That's one of the things we are very excited about and proud to do and something I'm not sure has been done before.
"To be able to give a huge sum to a children's charity in Paris, it's very special."
In the Barclays Premier League, Arsenal managed to complete the signing of Spanish defender Nacho Monreal on a 'long-term contract' for an undisclosed fee from Malaga just before the window closed.
Meanwhile, West Brom's wantaway striker Peter Odemwingie moved the attention away from QPR's record signing Christopher Samba after he turned up at the west London club unannounced.
Samba joined QPR from Russian side Anzhi Makhachkala for a record fee earlier in the day, while Odemwingie arrived at Loftus Road on Thursday night without permission from his club, confident of securing himself a deal.
A QPR spokesman confirmed to the media that Odemwingie was denied access at Loftus Road out of respect to West Brom, while the Baggies reacted quickly by releasing a statement.
It said: "The club can confirm they have held further discussions with QPR today but those talks have so far proven fruitless and no agreement has been reached.
"Albion would also like to make clear that Peter has not been given permission to speak to QPR about a potential move."
Rs boss Harry Redknapp announced minutes before the end of the transfer window that he also swooped on his former club Spurs to sign Jermaine Jenas and take Andros Townsend on loan.
However, Tottenham midfielder Jermaine Jenas did sign an 18-month permanent deal with QPR, while midfielder Alejandro Faurlin joined Italian side Palermo on loan.
Andros Townsend also joined QPR from Spurs on loan until the end of the season as Harry Redknapp looks to safeguard the club's top flight status.
Stoke were busy as they splashed out £2.5 million on United States winger Brek Shea from FC Dallas and signed England goalkeeper Jack Butland for an undisclosed fee.
Shea signed a four-and-a-half-year contract at the Britannia Stadium after the club made a successful appeal for a work permit earlier today, while 19-year-old Butland joined on a four-year deal from Birmingham - although he will immediately return to the Blues on loan until the end of the season.
Matthew Upson left the Potters and moved to Brighton on loan until the end of the season, while Rory Delap moved to Barnsley, also on loan.
Meanwhile, Norwich have signed striker Luciano Becchio from Leeds, with Steve Morison going the other way in part-exchange.
Becchio will join forward Kei Kamara, who joined the club on Wednesday from Sporting Kansas on loan until May, in the fight for a starting berth.
However, the Canaries failed in their numerous efforts to sign Celtic striker Gary Hooper, with the Scottish Premier League club declining several offers for the 25-year-old.
Sunderland also swooped for a new striker, completing the signing of Danny Graham from Swansea for £5 million.
The Gateshead-born frontman has signed a three-and-a-half-year deal at the Stadium of Light, just days after he was booed by some of the Black Cats fans when he appeared against them for the Swans.
As a result, Louis Saha has left the Wearside club by mutual consent.
Elsewhere, Everton completed the signing of highly-rated Barnsley defender John Stones for £3 million on five-and-a-half-year deal in a late move.
Earlier, Wigan announced the signing of Paul Scharner on loan from Hamburg for the rest of the season.
Scharner is returning to the DW Stadium having spent more than four years with the Latics before leaving for West Brom in 2010.
AC Milan's utility player Urby Emanuelson has joined Fulham on loan for the rest of the campaign.
The 26-year-old, a left-sided full-back or midfielder, has 16 caps for Holland and played for Cottagers boss Martin Jol during his time at Ajax.
Fulham also acquired PSV Eindhoven defender Stanislav Manolev and Ajax midfielder Eyong Enoh on loan until end of the season.
Aston Villa sealed the signing of French midfielder Yacouba Sylla from Ligue 2 side Clermont Foot and secured Spurs midfielder Simon Dawkins on loan for the remainder of the season.
Tottenham goalkeeper Heurelho Gomes completed his loan move to German side Hoffenheim while the north London club also confirmed 19-year-old midfielder Alex Pritchard and Ryan Mason had joined Peterborough and Lorient, respectively, on loan.
Elsewhere, Liverpool goalkeeper Alexander Doni is returning to his native Brazil to join Botafogo on a free transfer while Newcastle signed Swiss teenager Kevin Mbabu from Servette for an undisclosed fee and later announced that Spanish striker Xisco's contract has been mutually terminated.
Reading did not add to the signings of Nick Blackman, Daniel Carrico, Hope Akpan and Stephen Kelly on deadline day as they were unable to complete a club-record deal in time.