The deal ends the 13-year tenure of previous owner Marcus Evans with three board members of US club Phoenix Rising now involved at the club.
It is said that Evans has sold Ipswich Town to the new group for a deal worth around £40million.
Evans, though, will hold 5% of the new company.
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But Ultimate control of Ipswich will be handed to an Ohio-based investment fund named ORG, which oversees a large US pension fund and owns 90% of Gamechanger 20.
Mike O’Leary, the former West Brom CEO, will be the League One club’s new chairman as they push for promotion back to the Championship
Ipswich Town recently appointed Paul Cook to replace Paul Lambert.
Indeed, the former Wigan and Portsmouth boss is eyeing a late charge for the play-offs, where the Tractor Boys could potentially meet Sunderland.
The incoming chairman O’Leary said: “We want our first remarks on completion of this takeover to be words of thanks to Marcus Evans.
"We have been discussing this sale with him for more than a year, and throughout the negotiations his love for the Club has shone through.
“He is a true supporter and all of us at Gamechanger 20 are extremely grateful that he has chosen to put his trust in us
“Marcus has invested considerable money, time and energy in Ipswich Town. His decision to waive much of the Club’s outstanding debt is one that deserves the gratitude of every single Ipswich Town fan."