US company New England Sports Ventures, owner of the Boston Red Sox, has completed its takeover of Liverpool FC.
The move comes after former owners Tom Hicks and George Gillett removed the temporary restraining order blocking the £300m sale on Friday morning.
"I am proud and humbled," said NESV head John W Henry. "I can't tell you how happy I am. We're here to win."
Hicks and Gillett may now take legal action in England to secure damages after dropping a claim lodged in Texas.
The claim in the Dallas court was for £1bn in damages, with the American pair claiming the deal was "illegal" and an "extraordinary swindle".
"We believe that once the English court finally has a chance to hear all the facts, a very different picture will be painted," said a statement from law firm Fish & Richardson attorney Tom Melsheimer.
Still, there was an air of relief as news of NESV's completed purchase emerged - a move that will allow major creditors Royal Bank of Scotland to be paid the £237m it is owed on Friday.
A club statement revealed: "The transaction values the club at £300m and eliminates all of the acquisition debt placed on LFC by its previous owners, reducing the club's debt servicing obligations from £25m-£30m a year to £2m-£3m."
That, in turn, means Liverpool's holding company is unlikely now to be put into administration, a move which could have resulted in a nine-point penalty in the Premier League.
Henry, facing a media scrum inside the law offices of Slaughter and May in central London, added: "We're going to do a lot of listening, we have a lot to learn, and we'll walk this path together [with the fans].
"We regard our role as that of stewards for the club with a primary focus on returning the club to greatness on and off the field for the long-term.
"We are committed first and foremost to winning. We have a history of winning, and we want Liverpool supporters to know that this approach is what we intend to bring to this great club."
Chairman Martin Broughton - who revealed he would fulfill "a transitional role while John works out how to run the club" in the foreseeable future - added in a statement: "I am delighted that we have been able to successfully conclude the sale process which has been thorough and extensive.
"The board decided to accept NESV's offer on the basis that it best met the criteria we set out originally for a new owner. NESV is buying Liverpool in order to put it on an excellent financial footing and continue to develop it internationally.
"This is a good deal which comprehensively resolves the pressing issue of the club's debt and should give staff, players and fans great confidence regarding the future of Liverpool FC."
Former owners Hicks and Gillett had earlier lifted the restraining order blocking the club's sale earlier on Friday, but not so that the current board could complete a deal with NESV.
Hicks was believed to be negotiating the sale of his shares with US hedge fund Mill Financial, who already own Gillett's shares after he defaulted on a £75m loan from the Royal Bank of Scotland in August.
But the Premier League rejected Mill's requests to undergo a fit and proper person test on Thursday, saying it could only negotiate with the Liverpool board.
The board - comprising Broughton, managing director Christian Purslow and commercial director Ian Ayre as well as Hicks and Gillett - had already accepted a bid from NESV by three votes to two for them to become the club's new owners.
Hicks and Gillett, who gave up hope of holding on to Liverpool at a court in Dallas on Friday, could now bring their legal fight to the High Court in London.
Steve Stodghill, the Texas lawyer representing Hicks and Gillett, added: "This outcome not only devalues the club but it also will result in long-term uncertainty for the fans, players and everyone who loves this sport because all legal recourses will be pursued.
"Mr Hicks and Mr Gillett pledged to pay the debt to RBS so that the club could avoid administration that was threatened by RBS. That offer was rejected.
"It is a tragic development that others will claim as a victory. This means it won't be resolved the way it should be resolved.
"My clients worked tirelessly to resolve these issues but RBS would not listen to any reasonable solution and the directors acted selfishly and illegally. Mr Hicks and Mr Gillett wanted to position this club for the future, but others have a different agenda.
"In truth, there is nothing positive from these events for Liverpool Football Club. That is exactly the opposite of what my clients wanted to achieve."
The Royal Bank of Scotland, however, vowed to "vigorously oppose" any attempts made to sue, saying in a statement: "RBS is pleased the sale of LFC to NESV has been completed.
"We are confident this will provide the foundation for the club and its fans to enjoy renewed success on and off the pitch.
"RBS is aware of reports that Mr Hicks and Mr Gillett may intend to pursue further litigation in relation... the English courts have described claims made to date as "not realistic and abusive". Any further claims against RBS will be vigorously opposed."
Hicks and Gillett have continuously sought to prevent the purchase of the club they bought in 2007 for £174m, holding the view that Liverpool is worth much more than the £300m NESV offered.
It looked as though the prospect of it going down to a final day on Friday might be avoided after the latest High Court ruling on Thursday when Mr Justice Floyd issued an anti-suit injunction that rendered Hicks and Gillett's temporary restraining order, which they put in place to try and prevent a sale taking place, ineffective.
But Hicks and Gillett eventually withdrew their restraining order on Friday morning as it became clear Mill Financial would not be able to become Liverpool's new owners.
Liverpool, who face Everton at Goodison Park on Sunday, are in the bottom three in the Premier League table after picking up only six points from their opening seven games.