Ritchie's recruitment from the All England Club, where he has been chief executive since 2005, was rubber-stamped by the Rugby Football Union board on Wednesday.
The RFU has been in a state of managerial upheaval since John Steele was ousted as chief executive in June, the fall-out from which was poisonous, damaging and expensive to the governing body.
But Ritchie is focused on maximising England's golden opportunity of hosting the 2015 Rugby World Cup.
"I am very proud to be taking up the role of chief executive at the RFU and am excited about the chance to further develop the potential that the RFU and the game offers," said Ritchie, whose starting date at Twickenham is yet to be confirmed.
"The opportunity to lead an organisation which I know has so many dedicated, talented people is one I relish.
"I believe English rugby has a very bright future, culminating in a once-in-a-lifetime home World Cup in 2015.
"I am determined to help rugby create a legacy from the tournament that will benefit the sport for generations to come.
"The RFU has great commercial partners and a very sound financial base, underpinning the development of rugby union at grassroots and elite level."
Ritchie was identified as the "standout candidate" from the RFU's shortlist, with the interview panel impressed by his experience in business, leadership and sports administration.
The 58-year-old Yorkshireman is a non-executive director of the Football League, which he represents on the Football Association council, and a director of Wembley Stadium.
The RFU could not confirm last night whether he will continue in those roles.
Ritchie has previously held chief executive posts with Channel Five and Middle East Broadcasting. He was vice president of global business at the Associated Press before taking over at Wimbledon in 2005.
"Ian clearly demonstrated the required knowledge and capabilities across a broad range of areas," said Ian Metcalfe, who chaired the recruitment panel.
"He was the standout candidate with his combination of business acumen, leadership qualities and background in sports administration.
"We could not have wished for a better candidate who is so highly respected across sport and the business sectors."
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