David Beckham has part funded the dual contract between AC Milan and LA Galaxy that allows him to play on in Italy.
The midfielder, 33, is to stay on loan at Milan until the end of the season before returning to the United States.
No financial details have been released but the Galaxy said the deal had been funded jointly by Beckham and Milan.
"I've been able to help myself stay in Milan, if I can put it that way," said Beckham. "It's never about money, it's always been about the football."
The former England captain had been scheduled to return to Galaxy on 9 March but wanted to make a permanent move to the San Siro.
The new deal follows weeks of negotiations between the two clubs during which Milan baulked at the size of the transfer fee Galaxy were demanding - thought to be around £12m.
Move was about football not money - Beckham
Beckham says his desire to play for a top club in order to cement his place in the England squad for the 2010 World Cup finals was the reason he took the decision to effectively fund the unique loan deal himself.
"The obvious [reason for staying at Milan] is giving me the chance to play in the 2010 World Cup. I have to do everything I can do to be involved in that," he added.
"Everyone knows how passionate I am about playing for my country and, if it gives me a better chance of being involved in that squad, I'll do anything possible to make that happen."
Beckham also has the option to trigger a release in his contract or remain with the Galaxy at the end of the Major League Soccer season in November.
But Galaxy coach Bruce Arena said: "Nothing has been concluded on that and we are going to play out the year."
Meanwhile, AC Milan chairman Adriano Galliani has spoken in glowing terms of the financial sacrifice Beckham has made.
Jan 07: Joins Galaxy
Jan 09: Joins Milan on loan until 8 March
Feb 09: Expresses desire to stay in Milan
8 Mar 09: Beckham says it is dream deal to play for both
15 July 09: Due back at Galaxy
"A lot of players show their affection just with words. David Beckham is one of the very few who has shown it with deeds," Galliani told Italian television.
"I won't cite any numbers, but I can say that the player has made an incredible economic commitment, paying a lot of money from his own pocket."
Beckham, who will take a month off after the end of the Italian season, is likely to play just six home games for the Galaxy during the 2009 MLS season, but Arena suggested his return to the US in the summer would have economic benefits for the Galaxy.
"David has brought a lot of attention to our league and he has been an important part of the league's business plan moving forward," he said.
"Him coming here mid-year is not perfect but I think it's a real plus. All professional sports leagues in the United States are in difficult times now with the economy and I think David returning in July will be a boost for MLS and for the Galaxy."
Beckham played a part in AC Milan's 3-0 win over Atalanta on Sunday
Beckham, who confirmed his family would remain in Los Angeles during his time in Italy, which is set to end on 30 June, added: "I'm really grateful to the LA Galaxy and AC Milan for making this dream deal happen.
"The perfect result for 2009 would be for me to help Milan to reach the Champions League and for the LA Galaxy to make the play-offs and win the MLS Cup."
After the deal was announced, Beckham helped the Rossoneri to a 3-0 win over Serie A rivals Atalanta, a result that pushed them five points clear in the final automatic Champions League qualifying spot.
"Beckham has done more than we could have possibly expected from him," said Milan coach Carlo Ancelotti.
"He has settled in very well with the squad and given a huge contribution up to now. He is very professional and we are all very, very happy that he is staying."
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