Nike is ending a 13-year deal to manufacture Manchester United's football kit.
In a statement, the American sportswear company said "the terms that were on offer for a renewed contract did not represent good value for Nike's shareholders".
It is thought that either Germany's Adidas or Warrior will replace them.
Manchester United did not qualify for this season's Champions League for the first time in 19 years.
The club suffered its worst ever Premier League finish last season after manager Sir Alex Ferguson left following 26 years in the job.
His successor, David Moyes, lasted just 10 months and Dutch manager Louis van Gaal takes over following the Netherlands' World Cup campaign.
Nike first signed the deal with the club in 2002 and on Monday unveiled a new kit for the 2014-15 season. It will be the last one bearing the Nike logo.
Nike said: "Manchester United is a great club with passionate fans.
"Any partnership with a club or federation has to be mutually beneficial and the terms that were on offer for a renewed contract did not represent good value for Nike's shareholders.
"We look forward to a successful final season with the club."
United's existing deal with United States firm Nike is worth £24m a year. As part of that agreement they were given a period of exclusivity to negotiate an extension and also retained the right to match any other offer.
But the company has decided against exercising either option.
A figure of £600m over 10 years has been discussed with the remaining bidders, which would dwarf the reported £31m a season Adidas pays to Real Madrid.
They have signed a number of sponsorship deals, including an agreement to rename their Carrington training ground.