A statement from the British outfit, which has eight Grand Tour victories to its name, said current owners Sky and 21st Century Fox had agreed a sale to INEOS who will officially take control on May 1.
The hugely successful team's future was thrown into doubt when British broadcaster Sky said last December it was pulling the plug on its 30 million pounds per year backing.
Team owner Dave Brailsford appears to have hit the jackpot, however, by convincing keen cyclist Ratcliffe to step in, a partnership that should ensure the likes of four-times Tour de France winner Chris Froome, current champion Geraint Thomas and rising Colombian Egan Bernal need not look elsewhere.
Team INEOS's first outing will be the low-profile Tour de Yorkshire starting in Doncaster on May 2.
"Cycling is a great endurance and tactical sport that is gaining ever more popularity around the world," Ratcliffe, chairman and CEO of INEOS and whose personal wealth runs to a reported 21 billion pounds, said in a statement.
"INEOS is delighted to take on the responsibility of running such a professional team."
Brailsford said it was a "hugely exciting" new chapter for a team already boasting 327 victories.
"It's great news for the team, for cycling fans, and for the sport more widely," he said. "It ends the uncertainty around the team and the speed with which it has happened represents a huge vote of confidence in our future."
The takeover is a boost to Brailsford, the former performance director of British Cycling, after a torrid few years in which the "clean" reputation of the team, and his running of it, have come under forensic examination.
Brailsford's "marginal gains" philosophy helped turn Britain's track cyclists into gold-medal winning machines at the Beijing and London Olympics in 2008 and 2012.
When he formed Team Sky in 2010 with an ambitious target of giving Britain a first Tour de France champion while employing a "zero tolerance" policy to doping, many were sceptical.
But it took only two years with former tracks star Bradley Wiggins hitting the jackpot by winning the 2012 Tour.
Kenya-born Briton Froome won in 2013, 2015, 2016 and 2017 to move second on the all-time list behind greats Miguel Indurain, Bernard Hinault, Eddy Merckx and Jacques Anquetil.
Sky's huge budget allowed them to cherry-pick the best Grand Tour domestiques to support their general classification riders - leaving rival teams struggling to compete.
Ratcliffe, 66, is no stranger to investing in British sport having ploughed 110 million pounds into Ben Ainslie's America's Cup project and Brailsford says he shares his own vision.
"I know that we have found the right partner whose vision, passion and pioneering spirit can lead us to even greater success on and off the bike," he said.
Reacting on Twitter, Thomas added: "Super happy the team can continue and stay together."