Mr King said the judge's ruling that he owned the rights to a half-share of all the boxers in Mr Warren's stable could cost the British promoter "tens of millions".
As first reported in The Independent on Sunday, Don King Productions Inc (DKP) launched the action against Mr Warren and others following the break-up of the two promoters' business partnership in December.
DKP argued that it retained a 50 per cent share of all the boxers managed by the partnership, including the WBA featherweight champion Prince Naseem Hamed and the Welsh fighter Joe Calzaghe. It also claimed the rights to half the profits generated by the boxers in the stable.Yesterday the High Court judge Mr Justice Lightman decided in favour of Mr King.
Mr Warren, who had fiercely disputed the American's claims, issued a statement saying he was "disappointed" by the decision. He rejected Don King's claim that in reality the judge's ruling amounted to a knock-out blow, saying key issues had yet to be decided at a main trial later this year.
Mr Warren's solicitor Stephen Davies said there would be an appeal against yesterday's decision, which was "one battle in a long war".
That appeared to be borne out within minutes of Mr King issuing a triumphant post-judgment statement, criticising Mr Warren's record in boxing. The Warren camp promptly responded by issuing a writ for libel.
The costs of yesterday's action, which was spread over nearly a month, were over pounds 1 million.
Mr King's spokesman, Peter Wilson, said: "Every fighter that Frank Warren signed up to December 5 1997 is affected by this judgment. If [Mr Warren] goes bankrupt they may well be able to find a better promoter."
Almost every boxing contract and TV coverage contract which Mr Warren had entered into belonged 50-50 to the partnership, and he was now legally obliged to buy them out of the partnership, said Mr Wilson.
A key finding of the judge was that Mr Warren breached his obligations to Don King under their contract when, without Mr King's involvement, Mr Warren went ahead and signed a deal with Mr King's main cable television rival, Home Box Office, part of the Time Warner group, for the US rights to show Hamed's fights.
Mr Warren had said that he felt Mr King should have done more to have clinched a television deal for Hamed with the Showtime company, with which the American promoter has a close relationship.
The first bout screened under the new HBO agreement featured Hamed against the American boxer Kevin Kelley at Madison Square Gardens in December 1997.
Mr King has recently entered a new partnership with the British promoters Frank Maloney and Panos Eliades, with whom he has arranged tonight's World Boxing Council heavyweight title fight between Lennox Lewis and Shannon Briggs in Atlantic City.
THE GREATEST HITS
Old favourites include "Hoochie Coochie Man", "Knocking On Heaven's Door", "Wonderful Tonight", his paean to his ex-wife, Patti Boyd, "Layla", which has become his signature song.
THE LOVE AFFAIRS
In 1974, Clapton boasted that he had slept with 1,000 women. His name has been linked over the years with some of the world's most beautiful women, including the actresses Michelle Pfeiffer and Patsy Kensit, the singers Cher and Grace Jones and the models Marie Helvin, Carla Bruni and Paula Hamilton.
In 1966, "Clapton is God" graffiti began appearing around London. Of this deification, he once commented: "I'm not God, just the greatest guitarist in the world." Other nicknames include "Slowhand", also a tribute to his guitar skills.
THE EARLY BANDS
His first group, formed in 1963, was the Roosters, whom he left for the Yardbirds. When the latter drifted away from rhythm 'n' blues, he moved to John Mayall's Bluesbreakers; after that, he formed Cream with Jack Bruce and Ginger Baker. Then came Blind Faith and Derek and the Dominos.