The 60-year-old replaces Paul Murphy, who in turn will take over the role of RFU president from Willie Wildash.
Beaumont, a former England and British & Irish Lions captain, is excited by his new post.
"I'm very honoured to be appointed chairman of the RFU," he said.
"I was fortunate enough to captain my country and everything since then has been about putting something back into a game that is important to so many people.
"We all want to make the game as attractive as possible for all the men, women, boys and girls, who want to play and watch at every level.
"The RFU staff and thousands of volunteers face three years of hard work ahead but the legacy of England hosting Rugby World Cup in 2015 will be enormous and it is our chance to showcase our game throughout the whole country."
Lancashire-born Beaumont won 34 caps with England between 1975 and 1982, captaining them to a first Grand Slam in 33 years in 1980.
He has also represented the RFU on the International Rugby Board Council, including a four-year term as vice-chairman, and has been a director of the Six Nations and the Rugby World Cup.
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