The £36m deal was only renewed by the mobile giant for a further four years last summer and today's announcement will no doubt fuel speculation that the football club's new owners, the Glazer family, did not want to continue to work with Vodafone.
The announcement brings to an end a relationship that began when Vodafone took over as shirt sponsor from Sharp in early 2000.
In a joint statement, the two said: "Manchester United believes that the shirt sponsorship market has greatly increased in recent years, while Vodafone wishes to build on its successful sponsorship of Manchester United in new and exciting areas."
On its official website, Man United confirmed that it would be looking for a global sponsor and that initial discussions with international brands had proved that there was interest in such a deal.
Andy Anson, Man United commercial director, said: "The Manchester United shirt is the most iconic in sport. The club feels that, in the current market, there is a genuine chance to attract significant additional investment."
Man United will be looking to rival Chelsea's record-breaking £50m deal with Emirates, which was agreed this summer.
Vodafone has already announced its continuing involvement in football by confirming today that it is partnering with Uefa to become the official mobile network of the Uefa Champions League.
The three-year multimillion-pound deal, which comes into effect next July, will see it offering a range of mobile services around the premier European football competition.
The opportunity to sponsor Manchester United comes as the team struggles to remain in the Champions League having drawn nil-nil at home last night to Villareal and losing iconic captain Roy Keane, who sensationally quit the team last week. The team has to beat Benfica in Lisbon on December 7 to remain among Europe's elite teams.
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